So by adding those two sites, I've greatly increased the readership. Amazon is particularly useful for reviewers because of their ranking. As I've risen through the numbers, I've noticed a huge increase of hits at WordWeaving and many more review requests. I limit my reviews to three places because folks don't like reviews that are 'posted all over the Web,' which in discussion seems to mean five to 10 places. For reviewers who post their work at WordWeaving, I also encourage them to post other places as well.
Reviewers always retain ownership of their work.
You don't have to agree with the review, but if it is done well it tells you some things about the book, its subject and presentation method and design. That to me is an invaluable time saver. I still prefer to form my own opinion regardless of what a review says, but for a busy person it could save me time if the title and the story are two different interpretations instead of what the title led me to believe. Every writer is aware that reviews are subjective and the opinion of the reader. And, that is who buys our books, readers.