Without a specific nation with it's own way to play the game. There is no reason to play any of these Civ clones. The only reason I play Civ so much is because each civ gives it's own strengths and weaknesses. Otherwise I'm just playing a loop game with no real objectives.

So I really enjoy this one. This is why:
1) It is a much more historic-minded take on a the historical 4X game. Unlike say Civilization which assumes your civilization has immutable characteristics from the dawn of time, Millennia takes the idea that environment, neighbors, resources, etc. are what shaped a civilization into what it is. You are building your civilization as you play, and by the end of the game will end up with a civilization that differs from others to a depth you are not going to see in classic historic 4Xes, and feels organic based on both your choices and how history evolves.
2)The alternate history ages are really cool and generally feel very distinct. Each one has its own improvements, buildings, and special mechanics, and can have a big impact on how the game plays out. I haven't seen all of them yet, but almost all the ones I have seen are very cool and I look forward to see the ones I am not aware of and what modders and DLC will do with them over time.

3)As you get the hang of it, you'll probably start to appreciate the systems, and how the game progressively introduces them. Early on in the Age of Stone and even Age of Bronze you won't have much to manage. By the late game, you're spinning dozens of plates, but assuming you know the basics of how to spin a plate in this game, the number added doesn't really matter all that much because they're added gradually.

4)No, the biggest issue with Millennia is the AI. Your half-witted rivals, possessed of the viciousness of a school of piranha and the memories of goldfish, are adequate enemies but extremely poor diplomatic partners – a fact a bit too reminiscent of my old favorite. Sure, they play the technical game well enough: against Adept AIs (the default) it's hard to be the tech leader and control what age the world goes into, at least unless and until you do something to really establish your heft (like using the Age of Blood to render yourself alone on a continent, say). But your options for talking to other nations are bare bones without sending an envoy on a frustrating mission of getting roadblocked by “friendly” units, and still anemic if you do manage to get there. I understand some things, like repeatedly begging for open borders when denied, but even among themselves the AIs will make and cancel agreements with startling rapidity, allowing the player to watch a procession of one-turn wars and peaces if they're fortunate enough to have met everybody.

5)Other than that, while the overall art quality doesn't precisely bother me, there are a few nagging UX sorts of complaints. For instance, winning doesn't necessarily feel good or momentous: you get a honking fanfare and a popup that features, at least in the case of the wins I've yet done, the age art. Come on, even Civ 2 gave a very rudimentary animated cutscene with its own few seconds of musical score for victory! There's no “one more turn” option either; objectively minor and probably unnecessary, but who hasn't at least once won a relatively peaceful game and then in the postscript gone psycho and burned down all those infuriating AIs?

6)Complaints about RNG do seem valid to me; some games seem much easier to me than others. But I'm approaching that as a puzzle--a sign that there are aspects of the game I don't fully understand. And I'm seeing some evidence that's right, because I've been finding some ways to adapt to various starting conditions to get to a solid mid-game state. Frankly, the biggest issue I've found is that, when you play on the "continents" map, you have no way to interact with what's going on on in the other hemisphere, and sometimes one of the AIs will blob up before you get to a tech level where you can do anything about them. Perhaps that can be improved with fine tuning, but, for me at least, it doesn't ruin my enjoyment that I can't win every game. Likewise, more options for setting up the game--especially map types--would be welcome. And I expect they're coming--in fact, looking at the roadmap, I know at least one is soon to be delivered.

Millennia attempts to revitalize the 4X formula established by Civ games, and does a good job of doing just that.

This is one of the best strategy games I have ever played. You have to make prerequisites to advance to new ages, Enlightened, Basic, or Crisis ages, balance out your national spirits, and prepare for the future. This has Civilization beat hands down, and I've been playing that since it came out, can only polish a turd so many times. This is a whole new spin on the genre and please try it and pass it along to others. More people the better cause I know this is an instant classic, just needs more players and reviews.
I'm going to say if you are not ready for a real challenge, and use to things being handed to you, or you want a cake walk where you only have to play a game once to get it, don't get this game. Nobody likes a whiner.