Imagine sitting there at your computer, trying to play a game and someone is standing right beside you screaming in your ear the whole time. I liken playing COD 2 to that. It's pretty much full-on all the time. You barely get a single moment's piece. Go go go! In COD 1 there were parts like that and some more quiet. I didn't finish this game because it no longer has that balance. It's just frenetic, fast paced chaos nearly all the time. Well, at least judging by what I saw of the game, which wasn't all that much because that's not my idea of fun. If it is yours, then you'll have a blast. Just don't play it if you have problems coping with stress.
Technically it's awesome. It looks great and the AI is terrific but beware, it's another system hog. I had sluggish performance on my 6800.
I didn't like the health/damage system. Unlike every other FPS you've played, when you take damage you will more or less instantly heal automatically. You can really only be killed by grenades (which happens a lot) or if you just stand their taking fire like an idiot. I got nailed by rifle and machine gun fire all the time and just shrugged it off like Wolverine from X-men. To me this is stupid and ruins the whole experience, but I think they did this in order to maintain the pace and high intensity of the combat. If bullets could kill you, you'd be getting killed ever five seconds.
The other thing is there's no save game function. The game saves at checkpoints so be prepared to be doing stuff over a few times.
It's not really fair to review a game I haven't finished, but I just can't take another minute of it.