Electronic textbooks are rubbish compared to paper textbooks. They win only on weight and ease of copying (they should win on price, but the electronic version is often more expensive than the paper version). I have many of my textbooks in both electronic and paper format and the electronic version is what I use when I'm away from my paper, as the "better than nothing" backup.
The usability of a paper textbook is far superior. Easier to add my own notes to (notes which, I might add, I can be sure will be there the next time I read it, and the next, and forever), easier to write and draw on, easier to add my own coloured sticky tabs, easier to have five or six open at once, easier to literally put my fingers in it and flick back and forth to compare, and a fixed format that I know will be usable five, ten, and fifty years from now. Also more pleasant to read (except for those grey market overseas editions which sometimes are not well printed and on bad paper, but at one-tenth the price it's a fair trade-off!).
The usability of a paper textbook is far superior. Easier to add my own notes to (notes which, I might add, I can be sure will be there the next time I read it, and the next, and forever), easier to write and draw on, easier to add my own coloured sticky tabs, easier to have five or six open at once, easier to literally put my fingers in it and flick back and forth to compare, and a fixed format that I know will be usable five, ten, and fifty years from now. Also more pleasant to read (except for those grey market overseas editions which sometimes are not well printed and on bad paper, but at one-tenth the price it's a fair trade-off!).