I really hope the multiplayer is good, Ghosts was fucking terrible and I regret buying it.
This is my concern. I hated MW3 and I hated Ghosts. Sledgehammer assisted on MW3, and I thought they helped on Ghosts as well but google doesn't reflect that sentiment. BLOPS 2 I ultimately loved very much for the pick 10 system, the new equipment, and the feeling that I needed to have several very different classes for different situations but the maps are very hit or miss for me. Honestly, I feel that each new CoD has fewer and fewer maps that I love.
If Sledgehammer worked on MW3 but not Ghosts, then maybe MW3 shouldn't be pinned on Sledgehammer. I hope to like AW, but it's hard to believe a new studio will get it right on the first go. Map design is the biggest worry for me, as well as certain controversial issues like how they handle quickscoping. I disliked all of Ghosts' create-a-class changes and loved Pick 10, so I'm very interested to see in which direction Sledgehammer goes. Only time will tell, but I'll be there for the MP reveal for sure.
edit: I love CoD for 6v6 and small-mid maps. I like the progression systems and all the stuff to do outside of the match. I like the joystick tuning, which feels like perfection to me (as much as I love BF, this is the one thing that I always struggle with). I like the simple-but-effect radar (it's very readable and you get to know the blueprints on the radar as well as you know the level layout, eventually). I like the objective modes. And of course, I like the perks, killstreaks, and create-a-class. What I hate about CoD is dropshotting, quickscoping, people running around like crazy, etc. Maybe that's why WaW was my favorite--it was slower paced. Those jetpack images, while cool looking, don't build my confidence up much. CoD has progressively gotten faster and more ADD, which is fine, but it's not for me.