Here in Italy the percentage of ebook on total book selling is around 10%. It is not so high but it is not irrelevant.
For me ebooks changed completely my reading life: now I buy them if the books has no important photo or maps or similar things that need colours images and or great format pages.
In a pbook I can't change the font, the margins, the font size (I often change it), if I don't like its formatting I can't do anything...