I bought the app for my approximately 1 year old Kindle Fire HD and am just thrilled. Since I have more than a thousand books in my library Calibre, I was afraid that the problems would be. But that was not the case. The transfer of wireless works flawlessly and has about approximately lasted 1/4 hour, then my books were clean sorted on the Kindle Fire HD. Clicking on the book and it shows an all entries to be made in the Calibre library on your computer and that really all, even the columns you have created yourself in the library. The books in the app you can sort by various criteria and you can also configure settings for - change under anderem- view. Could I have more than 5 points awarded then I would do that.
