So I guess I'm going to be the uncool guy who listens to "The Man" and "The Corporation". I get a lot of use out of reviews. They often give helpful information about gameplay, bugs, and other things that can make or break a game. I saw previews way early in development for Mafia II and I was thinking that even though I enjoyed the first game greatly, the setting and the gameplay style has been done and done to the point that it would just feel to same-y. The game comes out, reviews come out, and lots of them point out exactly what I was fearing.
I was really looking forward to Alpha Protocol, but then when it came out reviewers said a lot about horrible AI and game-breaking bugs. I'll still play the game eventually, but only when I find it really cheap or when I hear that a patch has come out that fixes the bugs.
You can just watch gameplay videos, but then developers aren't going to show the bad parts and the bugs. I appreciate reviews for giving me a filter. There's lots of games out there, so it's good to have something that gives me some sort of guide of what to buy now or wait until it becomes cheap, what to rent or what to steer clear of.