The multiplayer isn't anything to write home about, but so far, the campaign is pretty awesome. There's one part that i'm not enjoying too much, though; between the 4th and 5th(?...) mission there's a little side-mission that you play in a RTS style. I'm not a fan of that genre, so needless to say, I failed at that and didn't enjoy playing it.
I spent my first 2 hours on the multiplayer losing gunfights that I should have been winning, but eventually I went on youtube and found out from WoodysGamertag that, if I adjusted my search settings to find games with the "best connection," I wouldn't be put in such laggy games and I would probably win more gunfights (or at least the ones I deserved to).
Maybe i'll get more into it as time goes on, but right now i'm not digging it too much. I used to be able to rack up pretty good kill/death ratios in previous CoD games, but on this one it feels like i'm always breaking even or going negative.