Awesome, but it's got some serious issues. Also derivative in parts. Still, one of the best 360 games.
The gameplay is also great. The duck-and-cover mechanic works perfectly. Enemy AI is very well-done (I wish I could say the same for the team intelligence). There is a great selection of powerful and fun-to-use weapons, the active reload system works perfectly, and the chainsaw is satisfying on so many levels. Online and split-screen co-op is very well implemented.
Now, for the not-so-great parts; The voice acting is terrible. The music is okay, but gets repetitive after a while, as the same track is played during virtually every firefight. The story is virtually nonexistent (the backstory is great, but you have to care to actually learn about it). Some parts of the campaign are rediculously difficult (like the final boss), and for some reason the Insane difficulty is actually easier than Hardcore. Physics get a bit odd at times- the slightest touch will send a corpse flying. Graphical glitches are also present, like hi-res textures forgetting to load for several seconds after a level starts. Also, many parts of the game are derivative. The multiplayer is a rip-off of Team Fortress, the Torque Bow was taken straight out of Turok, there's a sound effect you will hear over the course of the game that was stolen from Prey, and the song that plays during the beginning of the end credits (not the Cole remix) was lifted from Fable. I could go on and on.
Still, don't let these things turn you off of what's easily one of the best games yet on 360. The gameplay is fresh, and the graphics are simply stunning.