O.k, I imagine we've all seen a lot of those "slap in the face" and "ruined it for me" reviews so I'm gonna cut straight to it.

F*** the Old Blood update. It is perhaps the least fun I've had with a game and I've played some godawful trash. The Warframe endgame has no respect for your time or patience and is terminally grindy and unappealing. Avoid it.

The Old Blood update really showed up some of Warframes flaws I'd been ignoring as well. The game gives very little feedback when you're taking damage amidst the action and explosions and enemies teleport/spawn behind you frequently even in areas you've cleared.
Combined, this means that you can be surrounded and shot from all sides very often, and in high level content unless you are using one of a handful of durability powers or sturdy Warframes you can and will be instantly or near instantly killed.
I have been killed many times for the crime of having a heavy gunner spawn behind me or been evaporated in one hit by a random mook with a boxing glove that I walked past trying to defend an objective. Then the objective exploded in a literal second. This is horde shooter/slash-em-up, so every single enemy being able to do this produces expected results.
The main way to get around this is by running around and dodging everything, but half the enemies in the game have either knockdowns or a difficult to anticipate form of crowd control to shut you down and give everything else nearby the 1/2 second needed to kill you unless you went in beefy or have some sort of optimised blender build.
That's not even including bosses or the enemies like bursas that are designed to piss you off either. This is just regular high to highish level gameplay.
As it is, the only way to win those engagements is to go full meta and have absolutely no fun with a meagre handful of Warframes and builds or not play endgame at all. I recommend that last one, especially with how long it takes to upgrade your stuff and grind the stuff to upgrade your stuff, and grind the stuff to grind the stuff to upgrade your stuff (no really, that is a very common occurence).

There's more of course. More frustrating timewasting cheap difficulty gameplay, but that's enough to set the tone for now, because this is all just the groundwork for the bed of crap that is the Old Blood.
So, quick version: in the Old Blood update they introduced a Nemesis System. Shadow of Mordor it ain't trust me. They also introduced a bunch of cool weapons. Naturally, as I like Warframe's weird gun porn vibes, I try to get the coolest and dumbest looking one I can see, a burst-fire pistol that looks like a ♥♥♥♥. This is where we run into problems.

Now, in this nemesis system you get assigned a nemesis with stats determined by the Warframe you first encountered it with and a random gun. They not have the one you wanted? Oops! Have to kill them and cross your fingers the next one has it! Duplicates are a too thing btw, so good luck.
This nemesis, or "Kuva Lich" as it's called in game, then stakes out a portion of the map as its territory and steals a percentage of your stuff whenever you do a mission there (fun stuff already). The Lich has thralls in these regions, and killing them gives you info on what runes you put into your little Assassin's Creed arm dagger to perma-kill them. You get these runes randomly from new relics (think loot boxes you don't have to pay money for) that you also get randomly from certain existing missions.
Then once you have these three random runes (that expire after three uses so there is no escape from the relic grind) you slot them in your arm dagger thing, go into a nemesis mission (that you hopefully still have open because you can actually do them all and lock yourself out of ever killing your nemesis because they only appear in them) and stab them with it, fingers crossed the runes are in the right order.

Oh yeah. The runes need to also be in the right order in addition to actually having them in the first place.

No, the game doesn't tell you the order either. You have to figure it out by trial and error. And every time you do that and don't get them wrong the Kuva Lich kills you and levels up, making it harder to kill next time. You are punished for failing something you couldn't have possibly known for no reason other than to waste your time.

So to summarise, when you spawn a Lich you have a chance to hjave it have the gun you want. Once it's spawned kill 150 thralls that spawn maybe 5 times a mission to see what runes you need to kill it. From there spam Kuva missions for a chance at the relic that has a chance at containing the rune you want. Neither or those odds are particularly high. From there slot them into your arm-dagger-thing, go to a Kuva Lich mission and hope you're lucky. If not your Nemesis does their best Bane imitation and breaks your spine, levelling up. Back to square one. Time to kill 50 more of those thralls and try again. This all takes hours btw. Persevere though and at the end they die and you get a gun! Huzzah!

Also the gun has random stats. So the gun you get could be really crap compared to another person with the same thing. Not to worry though! You can always just DO IT ALL AGAIN and hope it's good this time!. Better hope that gun comes up on the Kuva Lich roulette wheel!

You can also convert Kuva Liches into allied summons after beating them but they are ♥♥♥♥, can't be summoned when you want them and last like a minute, so never ever do this. They are utter crap.

Also the Kuva Lich weapons you get are a massive upgrade sink, requiring you to reset their stats with Forma FIVE TIMES to actually fully level them. There are 13 of them. If you want full mastery on all of them not only do you have to jump through all the above hoops and hope you get them, but it'll cost you 65 forma. That's about £40 worth if you buy it with plat from the in game store or 1560 hours if you make them one at time like you have to otherwise from the in-game workbench, and that's not including farming the blueprints for them.
For those new to Warframe all other weapons except one require zero forma or stat resets to gain full mastery, and that exception is treated as a very strong unique end-game weapon. Gaining mastery on weapons and Warframes is how you level up too. It's a f***ing pisstake.

Think I've written a lot? This isn't even half of it. There's more. More and more crap to wear away at you and utterly waste your time.
I don't know what's going on over at Digital Extremes with this poor man's Shadow of Mordor crap that somehow outdoes Warner Brothers in making grindy unfulfilling gameplay and treating the player like a bloody chump. I have a job and ♥♥♥♥ to do DE! I don't have forever to spend monotonously trying to farm unnecessary runes and beat up some bland, uninteresting enemy in my very limited downtime to *maybe* have a little fun with a gun that'll take me 5 days of building Forma to master!

If you are gonna play this, avoid the endgame like the plague and don't invest too much into the game itself either. As it is right now, you are not gonna get a good investment of your time and potentially money. The game's still fun when it lets you actually have it, but it's mired in grind, frustration and boredom.

Warframe is one of many "time sink" style games going right now. Bear that in mind going in. It's still better than most, including the paid, full price ones, but it's not playing fair right now and you're not gonna get much out of it, especially endgame.
As it stands right now, I'd look elsewhere.

TLDR: Boring, grindy, f*** the Old Blood. DE, fix it.

Edit: DE have now added the ability to buy the relics and runes with their in game currency in the store! You know, those free loot boxes you acquire in game? You can pay for them now! To "save time".
Amazing. Create a problem and sell the solution. Not cheap either! Did EA buy DE when I wasn't looking?
I said avoid it before, double avoid it now.

O.k, I imagine we've all seen a lot of those "slap in the face" and "ruined it for me" reviews so I'm gonna cut straight to it. F*** the Old Blood update. It is perhaps the least fun I've had with a game and I've played some godawful trash. The Warframe endgame has no respect for your time or patience and is terminally grindy and unappealing. Avoid it. The Old Blood update really showed up some of Warframes flaws I'd been ignoring as well. The game gives very little feedback when you're taking damage amidst the action and explosions and enemies teleport/spawn behind you frequently even in areas you've cleared. Combined, this means that you can be surrounded and shot from all sides very often, and in high level content unless you are using one of a handful of durability powers or sturdy Warframes you can and will be instantly or near instantly killed. I have been killed many times for the crime of having a heavy gunner spawn behind me or been evaporated in one hit by a random mook with a boxing glove that I walked past trying to defend an objective. Then the objective exploded in a literal second. This is horde shooter/slash-em-up, so every single enemy being able to do this produces expected results. The main way to get around this is by running around and dodging everything, but half the enemies in the game have either knockdowns or a difficult to anticipate form of crowd control to shut you down and give everything else nearby the 1/2 second needed to kill you unless you went in beefy or have some sort of optimised blender build. That's not even including bosses or the enemies like bursas that are designed to piss you off either. This is just regular high to highish level gameplay. As it is, the only way to win those engagements is to go full meta and have absolutely no fun with a meagre handful of Warframes and builds or not play endgame at all. I recommend that last one, especially with how long it takes to upgrade your stuff and grind the stuff to upgrade your stuff, and grind the stuff to grind the stuff to upgrade your stuff (no really, that is a very common occurence). There's more of course. More frustrating timewasting cheap difficulty gameplay, but that's enough to set the tone for now, because this is all just the groundwork for the bed of crap that is the Old Blood. So, quick version: in the Old Blood update they introduced a Nemesis System. Shadow of Mordor it ain't trust me. They also introduced a bunch of cool weapons. Naturally, as I like Warframe's weird gun porn vibes, I try to get the coolest and dumbest looking one I can see, a burst-fire pistol that looks like a dick. This is where we run into problems. Now, in this nemesis system you get assigned a nemesis with stats determined by the Warframe you first encountered it with and a random gun. They not have the one you wanted? Oops! Have to kill them and cross your fingers the next one has it! Duplicates are a too thing btw, so good luck. This nemesis, or "Kuva Lich" as it's called in game, then stakes out a portion of the map as its territory and steals a percentage of your stuff whenever you do a mission there (fun stuff already). The Lich has thralls in these regions, and killing them gives you info on what runes you put into your little Assassin's Creed arm dagger to perma-kill them. You get these runes randomly from new relics (think loot boxes you don't have to pay money for) that you also get randomly from certain existing missions. Then once you have these three random runes (that expire after three uses so there is no escape from the relic grind) you slot them in your arm dagger thing, go into a nemesis mission (that you hopefully still have open because you can actually do them all and lock yourself out of ever killing your nemesis because they only appear in them) and stab them with it, fingers crossed the runes are in the right order. Oh yeah. The runes need to also be in the right order in addition to actually having them in the first place. No, the game doesn't tell you the order either. You have to figure it out by trial and error. And every time you do that and don't get them wrong the Kuva Lich kills you and levels up, making it harder to kill next time. You are punished for failing something you couldn't have possibly known for no reason other than to waste your time. So to summarise, when you spawn a Lich you have a chance to hjave it have the gun you want. Once it's spawned kill 150 thralls that spawn maybe 5 times a mission to see what runes you need to kill it. From there spam Kuva missions for a chance at the relic that has a chance at containing the rune you want. Neither or those odds are particularly high. From there slot them into your arm-dagger-thing, go to a Kuva Lich mission and hope you're lucky. If not your Nemesis does their best Bane imitation and breaks your spine, levelling up. Back to square one. Time to kill 50 more of those thralls and try again. This all takes hours btw. Persevere though and at the end they die and you get a gun! Huzzah! Also the gun has random stats. So the gun you get could be really crap compared to another person with the same thing. Not to worry though! You can always just DO IT ALL AGAIN and hope it's good this time!. Better hope that gun comes up on the Kuva Lich roulette wheel! You can also convert Kuva Liches into allied summons after beating them but they are shit, can't be summoned when you want them and last like a minute, so never ever do this. They are utter crap. Also the Kuva Lich weapons you get are a massive upgrade sink, requiring you to reset their stats with Forma FIVE TIMES to actually fully level them. There are 13 of them. If you want full mastery on all of them not only do you have to jump through all the above hoops and hope you get them, but it'll cost you 65 forma. That's about £40 worth if you buy it with plat from the in game store or 1560 hours if you make them one at time like you have to otherwise from the in-game workbench, and that's not including farming the blueprints for them. For those new to Warframe all other weapons except one require zero forma or stat resets to gain full mastery, and that exception is treated as a very strong unique end-game weapon. Gaining mastery on weapons and Warframes is how you level up too. It's a f***ing pisstake. Think I've written a lot? This isn't even half of it. There's more. More and more crap to wear away at you and utterly waste your time. I don't know what's going on over at Digital Extremes with this poor man's Shadow of Mordor crap that somehow outdoes Warner Brothers in making grindy unfulfilling gameplay and treating the player like a bloody chump. I have a job and shit to do DE! I don't have forever to spend monotonously trying to farm unnecessary runes and beat up some bland, uninteresting enemy in my very limited downtime to *maybe* have a little fun with a gun that'll take me 5 days of building Forma to master! If you are gonna play this, avoid the endgame like the plague and don't invest too much into the game itself either. As it is right now, you are not gonna get a good investment of your time and potentially money. The game's still fun when it lets you actually have it, but it's mired in grind, frustration and boredom. Warframe is one of many "time sink" style games going right now. Bear that in mind going in. It's still better than most, including the paid, full price ones, but it's not playing fair right now and you're not gonna get much out of it, especially endgame. As it stands right now, I'd look elsewhere. TLDR: Boring, grindy, f*** the Old Blood. DE, fix it. Edit: DE have now added the ability to buy the relics and runes with their in game currency in the store! You know, those free loot boxes you acquire in game? You can pay for them now! To "save time". Amazing. Create a problem and sell the solution. Not cheap either! Did EA buy DE when I wasn't looking? I said avoid it before, double avoid it now.