Modernwarfare 2 has pros and cons:
Pros:
Solid Campaign
Expanded Multiplayer
Better split screen Multiplayer
New Multiplayer tweaks like Game Winning killcam and Ability to join your friend's game quickly (Consoles)
Chooseable kill streaks
Spec Ops
Cons:
A few multiplayer weapons/perks/weapons are a bit unbalanced/overpowered
Map Packs are a rip off
Spec ops are only 2 players, not 4
Also, for all of you guys who complain about scream 12 year old on mics, you know there is a mute option, right?
I still think ModernWarfare 1 is a bit more balanced though.