A few month ago, a writer friend of mine posted on my Facebook Fan Page that Amazon does not let you add reviews about your work to book's listing. This was news to me but I didn't see the importance -- at least not immediately. That came later when I had some reviews of my work to collect and centralize.
Let me step back here and make a few points clear. As a writer, I rely on reviews of my work to help sell it. Good reviews or -- God help me -- great reviews need to be available with very listing of the book. At least ideally. But that's not how it works. If I've a got the book in Amazon, Smashwords, and a few other places, there's no way to share the review. This means that a review on one site can only live on that site. In order to collect them I have to copy them elsewhere.
This is very obnoxious and hurtful because reviews directly influence sales. If I've got a great review that I can't add to my book listings then readers cannot see the whole picture and may defer purchase of my book. And to be fair, Amazon is not the only place that prevents the posting of external reviews. Smashwords does too. Barnes and Noble, on the other hand, appears to let you post reviews of your book.
So my choices are to collect the reviews from all sites and post them on a web site or a Facebook page and promote that location. Links to specific sites can be used to when readers want to buy the book.
Or I can post all my reviews on Barnes and Noble and hope people shop there. But that does not help me get sales from the readers who stumble into Amazon and see my book but not the great reviews.
Frankly, I think this gives Amazon too much power over the success or failure of my work and is one more barrier between me and the reader.