Book Creator for Chrome has been updated over the summer. It has some really nice features which makes it the go to app for book creation.
One nice feature which was not obvious to me was right clicking on text brings up a formatting. Book Creator gives you some useful text features including increasing size, changing fonts, shadow, text color, and text background color.
The ability to add narration is really big in that it allows students an additional way to convey information as well as narrate their book. I like the video option but would caution to keep it real short. Think of it as a brief intro to the book or an animated photo. Larger videos tended to buffer a lot.
I think Book Creator for Chrome will be a hit with teachers and students.