It doesn't really help when Treyarch released the game before it was "finished". While I agree that MW2 had it's problems, it was a decent game. If not decent, than okay, but 10 x better than Black Ops.
The way the game was structured just appeals to me more than BO. Getting emblems and titles in MW2 spurred me to play more, and when my gameplay improved, I joined GB to play competitively. But with BO, there's no real drive to continue playing except maybe getting the pro perks. Nobody even does the contracts, and getting high kill streaks is just a matter of camping. As for zombies, it was fun after a while, but not enough to get me hours playing. All in all, BO was good, but it most certainly did not live up to the hype that was created, just like MW2 did not live up to all its hype (even though it did a pretty good job).

I'm just pissed now that whenever I want to go back to MW2 to quickscope again, I have to deal with mostly all the games being hacked by cheap little kids who ruined the game after IW stopped caring. And while I hope that the new DLC for BO will make the game a little more entertaining, I doubt it. As for now, I'm taking a break from COD and am just roaming around in Fallout shotgunning super mutants and blowing up towns with my mini nuke. Now there's a good game.