1. I think they actually tried some interesting things with the single player. There's a proto RTS segment, you play as a bad guy for a bit, horsee's, mild branching paths. Very aggravating when it totally takes control to do something cool but perhaps this is better than press X to continue watching cutscene. Overall I'm interested in seeing where it goes. Gameplay is the same but some new toys are interesting. Wallhack scope.
2. Multiplayer: New toys and pretty good maps. Killstreak replaced by score streak so actually playing the fucking game will get you rewards. Missed MW3 so don't know how big a jump it was, but feels more solid than Blops 1 overall.
3. Zombies: Blops 1 only had 2 maps, so three mpas and two modes is an improvement. Locations and weapons/stuff seems a little more varied but plays almost exactly the same. Run backwards and shoot them in the head til you get flanked and die because your teammate insisted on knifing in round 5.