Authors and readers alike are curious how this will play out, but so far there seems to be a lot of interest. I have enrolled one of my books, A Graceful Death, in the program which is called KDP Select. The initial period that an author, who has enrolled a book, is required to keep their book on the program is 90 days and the e-book cannot be for sale on any other site.
Note for authors: It takes several weeks to get your e-book removed from Smashwords.Com and Barnes and Noble. According to the Smashwords site, it may be a week or more before they remove an e-book once you have selected "Unpublish" from the dashboard. Smashwords then notifies Barnes and Noble and other sites, but it may take a week or more for it to be removed from those locations too.
If you have a Kindle, take a look at the program and try it out for a month, you may find it's something worth continuing. I'd be interested to know what Kindle readers think, please leave a comment if you've tried Amazon Prime.
I may enroll other novels, but I intend to see how this works out first. Meanwhile, look out for books that show Prime Members 0.00. The books that are available to Prime Members are still available for sale on the Amazon site so the only drawback for authors is that the book can't be for sale in digital form on Smashwords.Com or Barnes and Noble.
You can sign up for your free trial and upload A Graceful Death here.
