One word. DISAPPOINTING
The single player story is decent, but very short. I completed it in less then 5 hours and I know people who did this in less then 4 hours. The story isn't bad, but especially in the Delta Force campaign, the friendly characters don't really do something that makes them interesting. Compared to characters from the previous CoDs, I didn't give a damn when Sandman and that other guy I don't care about died.
Spec Ops is fun, although the missions are a lot harder on regular than they were in MW2, which, for the casual player is quite annoying.
The multiplayer should make up for the short campaign, but it doesn't. Little changes have been made compared to MW2, only a weapon level system and a new kill streak system. They implemented lag compensators, and that is the single WORST THING they have ever done to the series! Now, I get killed around corners, one-shotted by SMG's at long range and I often get 4 hitmarkers in a row, to get one-shotted by the Type 95 and in the killcam, the guy was already shooting at me for 2 seconds. I know this happened in Black Ops, but nowhere as bad as here. Rather than more open, gun on gun maps all we have is urban combat and camper paradise. Everybody camps with assassin and the type 95, and people who don't camp use one of the overpowered machine pistols, usually FMG9's. And now, I only end because my rant list is too big. I HAVE NEVER BEEN MORE DISAPPOINTED BY A SINGLE GAME IN MY LIFE