I'm more worried about things such as Killstreaks instead of Scorestreaks, return of claymores and mines, gun mounting, extremely fast TTK.
Im disappointed with no score streaks either, but apparently it's a perk option. Not sure how useful it would be though. There seem to be some things designed for score streaks like the Recon Drone field upgrade, and trophy system, etc.
Gun mounting should be fine since it exposes more of you than what you would assume.
As far as TTK goes: It seems like it's in a good spot, and TTK to me also depends on good map design.
My biggest issue with this game is the Stopping Power ability. I think it's just an awful idea and it will completely mess up the TTK.
I really hope they decided to remove/change SP Rounds. It's way too much of a crutch to win gun fights. I dont know who at IW loves Stopping Power so much.