What I'd really like to see is some cameo appearances by classic characters again. For instance, Cpt. Price was the leader of the British SAS at Pegasus Bridge in the first Call of Duty and he made a return in COD 2 and both Modern Warfares. I'd love to see some more old faces like Sgt. Moody or Cpt. Foley just as a throwback to the original.
I don't really play the games for the campaign, but MW2's was pretty excellent. The escape from that cave was epic. I can't wait to play the campaign in NYC. Going to be outstanding, but it'd be cool to see some of the familiar faces/voices. I think Ghost returns.
Honestly doesn't look any different than any COD game put out since the COD4: MW. I got bored of Black Ops after a month, the multiplayer just didn't have enough to keep me coming back. MW2 was a disaster on PC. I enjoyed COD4, but even that, there was nothing too interesting about MP after I finished all of the challenges/unlocks. I think the Battlefield series offers a lot more in terms of MP experience than COD. Oh well, people will still eat it up.