There's something off about this game and I can't fully place it? If you haven't played any Left 4 Dead's you'll probably enter this with an unbiased view and probably enjoy it if you're into this type of game.
I played the beta and about 3-4 hours of this full version. I will definitely keep playing but I'll share my thoughts. Be warned I will compare to L4D as it's very similar and the same studio made both.
PROS: Controls are great, graphics are great and optimization seems solid, I have everything turned up with no issues at all and my computer isn't high end. You get the same deal as L4D where you fight through a campaign against zombies, hordes and special infected. Lots of weapon choice and what seems like a somewhat promising AI director, though haven't really seen anything wild yet haha.
CONS: Bot AI is terrible, they get stuck on stuff a lot and sometimes do not help you as well as waste grenades. Special infected AI ranges from OP to abysmal, not sure if level design gets in the way sometimes. Ogre spawns sometimes in the dumbest spots causing it to get stuck and in turn does not seem very intimidating (can he not hit vehicles?) The Tank was much smaller but I remember it being a little more intimidating (L4D1 not 2 as 2 nerf'd him). Ridden seem lightless and like butter compared to the L4D infected. Sounds don't seem as distinct and memorable as L4D, characters seem more shallow.
I'm gonna give this game much more of a chance but so far it's a little weak and definitely feels maybe rushed? L4D seemed to have much more soul put into it.