I find it hard to read on a kindle or iPad much as I'd like the convenience.

One reason is that they are so much slower -- you can go from page to page in a flick of an eye or a quick page turn. Another is that it couples the somatic memory, making it easier to flip back to an earlier place (I often read in a random-access fashion, especially as I proceed through a book. The paper typography is still so much better in almost every case. And of course there's the reflected vs transmitted light issue.

I really don't care what other people think about my books and have most of them hidden away in the part of the house where guests are not invited.