lol, wow. Everyone who is a shooter fan MUST at least try the demo for this game. I just played through some single player and it's fantastic. This isn't hordes of shambling zombies. Once they start moving they are quick and there are several "boss" types that do different things. For instance the boomer who will explode. If you get the bile from them on you you become a beacon to nearby zombies and your group will get swarmed.
Trust me, try this one out.
Edit - ok, there do seem to be issues with their MP system setup and I don't know if they are going to carry over to release. Just an fyi in case someone is thinking of buying it to play the demo. There are apparently a limited number of servers for the demo that fill up rather quickly in prime time, it's difficult to setup your own server, etc.