Extinction mode is exilirating, but...
Single-player is just ok.
Toy-like weapons IMO, especially when compared to Modern Warfare series
Character motions seem less convincing than previous IW works
Multiplayer gameplay is kind of boring vs MW series
No ping/connection quality indicator in multiplayer
(...and I'm trading it in toward Gran Turismo 6 today while I'm still keeping copies of MW3 and MW2)