Awesome game, so far. I'm really enjoying everything about it. The guns and the maps are really good. Some of the perks are the same, but I don't mind. It's still a whole lot of fun.
I believe there are 13 maps in multiplayer. If I'm correct, COD4 had much less.
My only complaint right now is the tanks in some of the maps. Honestly, their not needed. This isn't Battlefield, and I've yet to use one, despite having several opportunities. It's not like they really affect the gameplay, but their just unnecessary.
I don't know what the critics have to say about the game, but I'm certainly enjoying it, probably as much as I did COD4 when it first came out. On another note, don't get this game for it's single player. I hear it's shorter than the one in COD4. That kinda sucks, but then again, single player is secondary to me in this case. I bought this game for it's multiplayer.
Another thing that kicks ass is hearing Keifer Sutherland in the game. Motivation from Jack Bauer! Oh and Gary Oldman, too. "UNLEASH THE DOGS!"
Speaking of which, I have to walk my dog. I'm probably going to play some of the single player when I get back.
Cheers!