With Amazon allowing reviews to be commented on, you get a lot of strange discussions. Most of the time, people can’t stand to see others didn’t like the book as much as they did. They post stupid back comments to one-star reviews “It is just abig book.” or “If you hated it so much, why did you read it?” or they do stupid things like point out grammatical errors or even more asinine, “Go write your own book before hating someone else” As if one needed to be a writer to be a book critique. Or those whose only comment to the reviews is something to the effect of how the review is an idiot, or an intellectual lightweight. this they only show by asserting their dubious intellectual cred.
To be honest, there are some inane reviews on Amazons, escpecially the one-star reviews. Personally I think that if you want well-reasoned review, look at the two-stars. They tend to be more rational and more informative.
However, the commenting has spurred some interesting discussions and there are times when honest discussion is borne, and rationality is restored. But yeah, these are rare.
Then we have the authors who comment on the reviews, which I find counterproductive. Though, I do think that it has the effect of making the reviews more polite. But more often than not, it makes the author look insecure and desperate. If you are an author, don’t comment on your book reviews. That only invites pain and shame.