I'm really glad I have a mostly Kindle and Audible digital library. I've been able to use my ebooks and Audible books without prob on my Kindle Fire (Android platform), as well as my iOS devices. And now I've added a Samsung Galaxy Note and can use them on another Android device. If I'd bought more from iBooks and iTunes, I'd be out of luck. As it is, I can't even load an iTunes audiobook onto a second iDevice without going through iTunes on computer.