Modern Warfare 3 is definitely the best Call Of Duty yet.
-The campaign is very exciting and takes place in 4 different continents. There are a lot of characters from the other games and a lot of surprises in that area. One of the down sides is it's still quite short, it's longer than the others but still not what you want.
-Multiplayer is quite fun, there are over 40 different guns, the emblems and titles are back from Modern Warfare 2 and there's a lot more customization. The maps are very good (you can't stay in one place for too long). One problem is the knifing system.
-The Special Ops are different, entertaining and diverse. And there is a levelling up system to unlock more missions, and guns and equipment for the Survival mode.
Over all, very good game and if you were thinking about buying it i'm telling do, it's worth it.