My Macroeconomics book was only available on-line and I absolutely hated it. Mainly not because of principle, or what have you, but currently all I have for my computer desk is a stool - and trying to read for hours a computer screen on a stool is not the most comfortable thing I can think of. I'd much rather have a book, to lay on my very comfy couch or a beanbag chair - whether I'm trying to read Macro (and stay awake) or a good book.
And besides staring at a computer screen for hours is not good foor your eyes.
