I am not very surprised......I like to use a combination of physical and digital copy of a book. Sometimes I just like to write down notes, hell lot of them while learning something new from a book, makes it lot more interesting and engaging.

Once I do some basic learning, its great convenience to be able to search for exactly what I want to refer by using search in the soft copy.

Features-wise, two things would be critical for me to switch completely to e-books:

1) Abitlity to take notes or jot down thoughts on the sides of the pages or markup/underline important sections - can't do without it, it would be too boring to even try reading without being able to do that.

2) Ability to look at multiple pages at the same time - can't do without that too. sometimes its just important for me to be able to look at different pages without having to scroll through the whole lot of pages in between

Coming to think of it, these are not impossible for a dedicated developer to do - probably the pages of interest could be tagged that would allow toggling and can be looked at in multiple windows within the same app window, like looking at multiple files in excel.

somebody gotta try it!