Pros:
Graphics
Being able to play Hardcore game types immediately
Starting weapons aren't as awful as they were in previous games
New Killstreak scoring system
New Killstreaks
Maps are varied and have tons of high and low access points
Pick 10 system to create a class that truly fits your style
Cons:
Spawns still suck something awful
You have to use the same Killstreaks for every class
Takes forever to rank up after the first 20 levels or so
Don't get new equipment until much higher ranks than I recall
Still cant figure out how to see the "Challenges"
Lack of true sniping maps, really only found one
If you don't use teamwork, its much tougher to win Deathmatch, no more Rambo-run-'n'-gun
My awful K/D
Overall, I like the game thus far. Maybe I am just being nitpicky.
