The problem is that reviews can easily be manipulated. I am especially leery when there are few reviews. It’s too easy for a publisher, author, or their proxies to write glowing reviews that overwhelm accurate ones.

Of course, this can also happen in the opposite direction. Where opponents of an author or topic flood a review area with disparaging remarks.

I like the idea that a person must have purchased a book in order to review. I’m not sure it’s really feasible to to this however. To some extent Amazon can do this, but it’s difficult for other forums to really prove a purchase.