The only reason I ever played the Xbox 360, this game is astonishing.
Let me start off by saying that you go inside a giant worm and kill it. Yeah, beat that Nathan Drake. My favorite level however is this really bleak mansion-esque place controlled by some lunatic guy that doesn't want you there. There's also this really cool cave, and etc. etc. etc.
The graphics are incredible, making full use of the xbox-360 gpu, and the sound is excellent and spot on in each location. The enemies are the same as the first for the most part but it doesn't detract from the gameplay. You are constantly fighting in bizarre fantasy places and although its a riot, I kind of wish there was a little consistency. Marcus Fenix is a badass, but still doesn't develop much as a character.
It is hard to review such a critically acclaimed game without saying "just play it" but that's really all I got. It is the only game I find the Xbox to be worth playing for along with Forza 3.
Pros:
Incredible bizarre environments
Very satisfying shooting
Cool enemies and allies
Cons:
Plot is non-existant
Guns aren't varied enough
It's on the xbox :'(