Just like I said before with Black Ops, just because a game is rated M doesn't necessarily mean it automatically should be ruled out for all age groups. I'd definitely let most 14-16 year olds play this game, no problem. It is a good game, the storyline's a bit lacking compared to other Call of Duty games, but, well, great game mechanics make it kind of worth it. There is that one scene everyone talks about, the part of the game that almost got the game banned in some countries, called "No Russian". This is exactly what that level is; you, an undercover agent for the United States, are ordered to stay close to a Russian terrorist in order to gather intel and eventually kill him/lock him up. You are ordered by your supieriors to do whatever it takes, whatever he tells you to do, because it is the only way you will be able to get close to this guy. The Russian terrorist leader orders you and several other of his men to go through a Russian airport, shooting every civilian in sight. This is the first time in Call of Duty games where the character is ASKED to kill civilians. However, you don't even have to shoot. You can just follow everyone and not shoot a single shot.
I realize that this is a very obviously violent scene. However, this game as a whole is not as intense and dark as Black Ops. And parents should remember NOTE**** that you can set the game's options to a non-graphic setting that will make it so that there aren't any blood effects when you shoot people, and you are asked at the beginning of this game whether you want to play it or whether you'd like to skip this scene. Without this scene...this game is an entertaining FPS that has great controls, not the best story but good levels, good voice acting, great graphics, (there is language, it is true, and thats just a matter of know your kid and how old they are). Overall....nothing in this game even comes close to the intense darkness of Black Ops, in which you are strapped to a torture chair, and there is a level in which you are locked by your own men into a gas chamber and have to watch the men dying very graphically around you, vomiting blood, eyes bleeding, skin corroding etc etc. Nothing like that in this game. Its pretty much Bang, Blood, enemy dead, swear swear, thats it. If your kid watches that on TV or in the movies anyway...why not?