I read Amazon reviews, especially on books, every day, often multiple times a day. I love reading and I love (very often) reading other people's opinion on books. I always start reading the one-star or two-star reviews. Why? Well, I guess because when someone is strongly against something, I want to know why they are. Was the book boring? Inaccurate? A pathetic attempt? Or the lonely one-star review was making reference to Kindle formatting or late delivery? It happens pretty often.
After having read one- and two-star reviews, I jump to three-star ones. They are often the most informative. Who is giving three stars? I know I am generalizing, but very often (I read and I am interested largely in non-fiction) it is some guy with deep knowledge of the topic, with an opinion, who can find strong and weak points , and for whom a three-star book is a book worth reading, with some caveats. Five-star reviewers are usually fans, and I do not care that much about fans' opinions.
Herbert Gintis is one of my favorite reviewers.