Well, look at Zelda Twilight Princess, Skyrim,... a lot of games that have been over 90 in rating, then look at the User score, it's actually between 8,5 and 10. The more reviews you get, the closer you get to what people think of it. Even if they are only judging the graphics, or the fact that it's a sequel, by adding together those reviews, you get an accurate view on what people thinks of your game.
Yay, gamers are judging like gamers, not like a magazine, which is way more interisting, as I am a gamer. Offering a hundred viewpoints on the same game, from people who played it is better than reading a magazine.
Technically, MW3 is probably a pretty good game, it has decent graphics and animations, some new maps, whole new story mode, new multiplayer modes,... But they don't tell you that the new maps are crappy for multiplayer, or that the story mode is pasted from MW2,... (exampes)
There is a reason MW3 is getting this rating, as for MW2, it's not because people hate it, it's because it just doesn't deserve more in the eyes of players.
