Be prepared for an intense campaign with a strong exciting multiplayer.
-Personally so far this is one of my favorite campaigns out of all Call of Duty games. I love the excitment! I strongly recommend to play Call of Duty 4 and Modern Warfare 2 before you start with Modern Warfare 3 to keep up with the story line. Be prepared for good challenge but don't expect it to be long.
Multiplayer: It has its ups and downs. The positive thing is new decent weapons, great maps, perks, killing streaks, and the whole new technology equipment.. even the little new customizable things make it even more sweet.
-The negative things are: Lots of people camping, some people on your team suck so bad sometimes makes you want to play free for all otherwise you'll lose a lot of the time. Unable to carry shotgun as a secondary weapon decreases the fun for me personally but you can still pick decent pistols and fully automatic handguns.. and yes of course there's still shoguns but you have to use them as a primary weapon of choice. Just be prepared for somebody to lay on a rooftop, behind a corner or by the spawn camping.
Overall: It's a great game if you like a nice average, exciting, intense campaign. It won't disappoint if you're into Call of Duty series. Also if you love a great first person shooter multiplayer action this game is for you. Be prepared for an intense war with a decent story. Enjoy!