if i rated mw2.... i would say poor story terrible community online 6/10
I really got spoiled when I first played GTA VC. So, now it's very hard for me to enjoy linear games with barely any freedom. With MW2, I would really take three points off for being an "average linear FPS", and then two points for its short singleplayer campaign. That would be a 5/10. Very low score, but I'm just that critical on that type of game when most of my games are now sandbox games.
I do agree with DarkxWater24 though. It's more of what you think, and big reviewers usually rate games depending on how much advertising they get (it seems).
For Yahtzee's Fallout 3 review, it seemed quite positive compared to almost everything else he reviews. The only one I watched that seemed very positive was for Saints Row 2.