It's a good start, but something is bothering me about having to pay on top of a physical book to get the ebook. While making the ebook is not free, I'd argue it's pretty cheap to make since you need a digital version of your book anyway before making a physical product out of it, and technically speaking buying a book means buying a license to read it - so why would you have to pay twice to access the very same content ? From a license viewpoint this should be free or close to free.

Or am I missing something?