Anything you would like too see Infinity Ward learn from, and include from, Black Ops?
It's quite a small thing but I'd like to see the varied assist xp from both World at War and Black Ops. No idea why it wasn't in MW2 but I can't see any downside to rewarding people with a few more points relative to the amount of damage dealt, it makes so much more sense to reward 80xp for 80% damage dealt instead of all assists being worth 20xp, regardless of damage.
I personally want only pistols and launchers as secondary again because otherwise it's as if everybody has a free Overkill perk and pistols become entirely redundant. Although this causes the problem of more people using launchers instead of pistols which makes air support less effective. Perhaps a nice fix for this could be going back to COD4 days and having anti-aircraft weapons as a perk.
The only other major thing for me would be no quickscoping again but that's already been confirmed to be in the game...