What reviews do for me is give me a little bit more in-depth info on the contents of the product- more than I'd get from its cover or a quick scan in the game store.
However, I don't pay much attention to the reviewer's actual opinion unless he relates the product he's reviewing to a product I already own, or unless I'm familiar with that reviewer's past reviews.
IOW, if he likes what I like, I'm more inclined to buy what he reviews favorably. If his opinion is generally opposite of mine, I'll go counter to his reccomendations.
There are no rubber stamp reviewers for me, though, and "stars" are, IMHO, useless.