I've taken a second look on the book and I have to admit that it isn't as bad as I thought first. The first time I was very shocked about the huge white border around the text but when using the first zoom (M) I think it is really ok. And on bright daylight the contrast is also manageable.
I have attached some fotos for you to see it yourself with different zoom levels.
It seems that the text reflow is quite ok when zooming (some of the spaces between words seem to get a little large, but it's ok to read).
However it's disappointing that the book it not optimized for mobile readers, it seems to be thought for reading on a bigger computer screen.
Anyway I can think I can go with that, but the bext books I'll buy (if any) will be in a more convenient format like the one from Sony.
BTW: The book is from here:
http://www.booksonboard.com/index.ph...ook&BOOK=19909