One thing I found and disliked about the previous CoD (MW3) was that, a lot of maps were rather small, or felt small because the corners were so tight. Or perhaps, that was just me but I tried to snipe quite a lot but never found a good enough spot or area I could snipe and not be cut off from a wide-view or area to get a clear shot.
I know a lot of people like "Quick Scoping" but I personally think that kills what Sniping is about. You're just aiming in fast and getting a (Most possible) one-shot kill. And, 'Rifles' in Treyarch's WAW, kind of made it feel like it was worth having a scope, so you could quickly scope in and out of the opposing players. But there was also the option to just have the rifle without the scope attached. Which I believe is being returned to in BO2(?). I'm not saying she should stop quick scoping or anything, what I'm trying to put across is that I liked it a lot better when you could be a sniper and feel like you are an unseen killer from afar.
Which I feel like MW3 had such tight corners to challenge that, or sniping in general. Though... That's just one of my opinions. But even then, a lot of assault rifles felt rather useless against people with SMG's, who had a better grasp on the mobile use of moving around and killing enemies fast.
I'm actually hoping in some way that Treyarch don't make the same mistake as Infinity Ward and kill the essence of real sniping, by over-complicating the game mapping.