I started to use it, but for me it quickly turned into a pain in the behind because of the limited file types allowed, and the way that it feeds on particular folders. In order to make it work, I'd have had to split my file types apart and keep a whole separate folder of acceptable file types just for Amazon to work with.
A few days after trying to make it work, and even getting together with Amazon techs about how best to manage it all, I just didn't see a really acceptable answer for me personally, so I pulled the plug on the whole idea and deleted all I'd uploaded already, then closed it down for good.