I created a personal picture book for my son, and it is easy to use and works great with iBooks. I havent tried to publish anything, so not sure about that aspect. It has options for exporting to overdrive, nook and Evernote, but none of those exported picture books looked right at all (tiny pictures...text/ other pictures covering each other). Perhaps it works fine for a text only ePub, but if I was doing text only, Id probably use epubbud on my PC.
Kimmyac about Book Creator for iPad