Good... But repetetive.
Now don't get me wrong. It's a good game. A very good game. However as I played through the cinematic sequences that were the levels I couldn't help but feel a certain repetition. As if I was doing the same thing, over and over. Sure the environment was different, but it was essentially the same thing:
Start off, fight off zombies, find occasional mutated zombie, flick switch, fight off zombies, fight off tank and then finally: do all of those at the same time.
And then there are the weapons. 6 weapons Valve? 6 Weapons is the best you could do? Two types of shotgun, pistols, uzi, rifle and hunting rifle. Oh yes, and then theres the ridiculously over-powered pipebomb, that attracts the zombies like a hundred alcoholics to a bottle of whisky, and then brutally blows them up in a shower of gore, which admittedly is very cool.
Nevertheless, the worst thing about the game is that it has no ending, though it might mean there will be patches with more levels.
But enough about the bad things, lets talk about the good things. With the dynamic lighting and the zombie dismemberment, It really makes you feel like your in a movie.
The best thing of all is the Versus mode. Pure genius. Getting together with your friends to either fend-off, or help the zombie apocalypse is chaotic and fun. So I think that the co-op and versus modes are the two main features of this game, and you definately should miss out on them.
In conclusion, only buy this game if you have constant access to internet. If you do then, What are you still doing here? You should be playing L4D?