Pretty good. I only play online so someone else can give you an idea about the campaign. But online... Better than AW... But still has some silliness to it. They toned down the burst moves. Still kinda ridiculous but I'll take it over AW any day. Love the maps so far. Kill streaks are badass.
It's not much different from the rest of them. My only complaint about it is that I keep getting put in games against people who are already 2nd and 3rd prestige in matchmaking when I've played a handful of games. I could have sworn they did a much better job of putting newer people together in games in Blops 1 and 2. The larger maps aren't an issue, but for the smaller ones all of the people who know the maps know the pre-fire spots in hardcore S&D. If you don't have a party together you're going to get smoked.
The peak of COD multiplayer. Not sure it will ever be beaten.
MW2 was the shit... Best online multiplayer out of the entire franchise IMO
