Well, with the departure of most of the core of IW, there were serious concerns heading into Modern Warfare 3. I wish I could say this game was an awesome game, I cannot say so. I liked the first two and this one, sadly, seems to be lacking in any real changes or updates to the formula. Tragically, I prefer the prior year's game more (Black Ops was awesome, in its defense, but it's odd to prefer Treyarch's work).
I recognize that I'm in the minority --- Elite is apparently selling well at $50 a pop for a collection of map packs and stats. But this game is just a total paint-by-numbers production. The game seems to work just fine. The weapons feel powerful. The game moves at a nice clip. The story --- OK, it's always been basically nonsense, so it's not any worse than usual.
There is a LOT of rail shooting in the game. A lot a lot.
The game, though, lacks fun. Just simple, hard to describe fun. It's not bad. It just lacks anything resembling a heart or soul. Activision, I fear, is actively killing this franchise. I hope it doesn't go as bad as their other dead franchises, but I don't see a lot of room for improvement with these titles, especially with them coming out so frequently.