If we're talking about a review in the New York Times or something like that, then yes, that's been known to get my attention. I first heard of Room because it got an awesome review somewhere, and now it's next on my to-be-read pile. Amazon reviews, not so much for books (appliances or products like that, yes). The only time I read them is when I'm already very iffy on a book or if I've heard something about a particular book and want to find out what the fuss is about (a character who dies, something like that). Oh, and I have been known to read the reviews for a particular author who's series has gone to crap because the reviews are more entertaining than the books now. And I even admit that the last one sounded so awful I was almost tempted to buy it just to see how bad it really was.
So if I read a good review somewhere that makes a book sound awesome I'll check it out, but I don't seek out reviews, and I don't read the ones on Amazon before buying most of the time.
Interestingly, the book I've despised most in my life is one I read not too long ago. Afterwards, I checked out the reviews. It had a four-star rating on Amazon, so even if I was checking them out I would no doubt have bought it. It just so happened that I thought all of the one-star reviews were spot on. I think that's the main reason I don't do it. My subjective opinion on a book isn't necessarily going to be the same as the subjective opinion of everyone else who read the book.