It's an improvement over every CoD that came after World at War(I LOVE World at War). The class system they've implemented(gear, perks, and wildcards) are much more diverse and balanced than in the last 2 maybe 3 games. While the matchmaking still has the notorious CoD lag spikes, they aren't nearly as frequent or severe as in BO1 or MW3. That said, I still prefer BF3 and Halo 4 multiplayer modes. Zombies mode is crazy fun though(as usual), different and takes some getting used to but fun nonetheless.
[Edited on 12.30.2012 1:33 PM PST]