Hmm...when I check out reviews, I tend not to look at the score they gave, but the review itself and the more different viewpoints the better. I examine what they said about the game, what the vids show me, what the pics look like, then make my own decision as to how good a game will be. I'm usually pretty spot-on with that.
One thing I've noticed, especially with IGN, is that it's obvious they didn't play much of the game they reviewed.
That said, IGN and Gamespot are the ones I watch most. 1up has ruined their site with a terrible design, and frankly, I don't really know of any other good sites for reviews/previews.
Maybe someone can list some good ones? I'd really like to add to my list of review sites....in English.