Ignoring the brouhaha that's been bubbling lately, this game is a must-have for any shooter, zombie, co-op, or multiplayer fiend.
The pacing is great, the audio cues are helpful, and the A.I. director is... good. I don't see how this feature is so incredibly innovative, when games like SIN Episodes already had adaptive and dynamic A.I. But, it does its job, and it does it pretty well.
To date, the game has three major modes: campaign, versus (where you can take control of the boss infected), and survivor (where you see how long you can last against waves of zombies). While many people are clamoring on about playing as the boss infected, I find the campaign to be the game's meat and potatos.
You can "finish" this game quickly, and it's up to you whether replaying the levels with the A.I. director is any fun. For me, the glow died out months ago, and now it's a fun but casual game to come back to every once in awhile.
A great game? Absolutely. Worth $50? Not so much.
Score: 8.0