Editorial reviews are different from customer reviews. They’re from reputable book review sources–such as Kirkus Reviews or Foreword Magazine, and they can add a great deal of luster to your book.
To add them, log in to your Amazon Author Central account (authorcentral.amazon.com), click on the image of your book, and then click on edit details. You’ll see the field where you can add your editorial reviews.
Keep your excerpts short, and bold your sources since they are the most compelling part of any review. And remember, you have to add your reviews to each format of your book: that is, if you have a softcover and a hardcover version, you have to add those reviews to each version. Takes a little longer, but it’s worth it.