==========2023 update==========
Killing Floor 3 has been announced, now where to finish this review.
After playing this game since it's beta Killing Floor 2 has had many ups and downs in it's lifetime, during early access and it's initial full release Killing Floor 2 kept getting better and better, eventually in 2019 they began introducing paid weapon packs which continued until the end of KF2s development.
It does seem that selling weapon packs and season passes/cosmetic season passes has been their main priority whilst working on KF3, though the guns are fun to use in game I still don't think they're worth their prices individually.
Looking forward to KF3 but staying cautiously optimistic.

==========2015 update==========
My original review was written upon the games release and its sad to see how much of a turn it has taken with the latest announcement.
The game costs £19.99 but from this time forward all additional guns will cost £8 to purchase for a pack of 1x Weapon and 5x Skins.
For almost half the price of the entire game you can get a single weapon, the price is still inflated when to compare it to the game's content at launch.
Tripwire have stated they will continue to give us free content but half of it is community stuff that they just pick and add in anyway.

Original review below


==================== THIS REVIEW WAS WRITTEN AND SAVED DURING THE BETA, SO PLAYERS KNOW WHAT IT WAS LIKE A LITTLE WHILE BEFORE FULL RELEASE==========================

Great game, where do I start?
Killing Floor 2 is a massive step forward from Killing Floor, with many new features and an amazing sound track!
The game visually has made a much larger improvement, more gore, better looking ZEDs, better looking characters, even the amount of corpses you can see on the map can be adjusted!

Keep in mind that this review is in the Beta stage, 4 days before the release on the 21/4/2015.
Here are my personal thoughts, chalked up to a simple Pros and Cons list.

PROS:
Very fluid gameplay, never a dull moment, the action is nonestop.

ZEDs have had a few little adjustments, including two new sub-types of clots. (The Slasher and the Cyst)

Those tough ZEDs you hate fighting, FleshPound and Scrake? Oh, of course they've been buffed and much more of a challenge!

Visuals. The game looks utterly stunning, it's always attracting me with the precious eye candy of ZED giblets flying around.

Soundtrack! The soundtrack KF2 uses gets your blood pumping, and your bloodlust too, for that matter, killing hordes of mutants is always better with some hardcore music in the background.

CONS:
A little too much chatter from the characters. (However, this can be disabled in the menu)

The loading screen can sometimes take quite a while, even for those with an SSD, however this is a 1/10 chance, I've found.

Loading the game up can be a task, though this is because Steam treats the game (as of beta) as locked, and can be a pain to actually get up and running. Note: I'm sure this will be resolved as soon as full release hits.



Killing Floor 2 is as unforgiving as the original, and I would 100% recommend it to old and new players alike.
For only £19.99 (Or £26.99 for the Digital Deluxe Edition), you'll find yourself immersed in hours of none-stop slaughter and fun.

A masterclass in level design and horror atmosphere.

Following the Unreal Tournament (2004) mod in 2005, Killing Floor comes as a standalone game.
It's your job to kill an onslaught of Horzine Biotech's specimens nicknamed ZEDs, you'll find yourself playing as various classes who specialise in different classes of weapons, from shotguns, assault rifles to flamethrowers and even melee weapons.

You can play with up to 5 other mercenaries, holding out on beautifully designed maps which capture that gritty, dark feeling that genuinely makes you feel like you're one of the last living creatures in your area.

The ZEDs come in various types;
You have your bog standard zombie-like brainless Clots
A fast and deadly Gorefast, wielding a machete as he sprints at you
The small and elusive Stalkers who turn invisible to sneak up on you
Even smaller Crawler who will pounce when you least expect it
The loud and screeching Siren who's call could burst your eardrums
The slow and gluttonous Bloat who's vomit is acidic
The intimidating, chainsaw wielding Scrake
And finally the alpha-predator Fleshpound, who's name is self explanatory

is it worth playing Killing Floor 1 in 2023? Absolutely, in fact if you've only had experience with Killing Floor 2 I'd highly recommend checking out Killing Floor 1 and seeing how different the atmosphere is.
The game still runs well to this day and the gunplay is just as engaging as it was back when I first bought it.
There are still plenty of players and finally, the game does have Mod Support you so you can enjoy a plethora of custom maps, weapons, RPG-like elements in servers, even up to 100 players in some custom servers.

Killing Floor 1 is an absolute must buy in my opinion.