Reviews are good for reading the actual contents of the review in my opinion, which is far better than just looking at the scores only(not saying you specifically do that, but a lot of people make that mistake). Often the reviewer says something like, "X aspect of this game is very bad and draws away from the experience", and then grades accordingly. But to someone who doesn't really care about X or doesn't think it's a big deal, he could make the judgement accordingly for how that would impact his potential enjoyment of the game. Reviews aren't mean to be an opinion on a plate you're supposed to swallow and accept completely, it's just telling you what their opinion is and it's up to you entirely whether your opinion matches theirs and for you to figure out for you to account for your and the reviewer's differences.
Woops, got into a bit of a rant there...it isn't targeted at anyone specifically but I felt like saying it..