Biella asks if I can read novels from a screen. Yes, I've read what has to be getting close to a thousand novels that way, over the past 8+ years.
I was thinking about this just the other day as I read The once and future e-book: on reading in the digital age. That article does a good job arguing against many of the common complaints about ebooks, such as "I can't read an ebook in the bathtub".
Right now, I have a pile of paper books I want to read or am in the middle of reading. But if I want something new to read, I don't reach for that pile, but for my (much larger) directory of ebooks. The pile of paper is reserved for special occasions: plane trips, camping, etc.
I started reading ebooks in circumstances where it was too hard to get access to paper ones. Traveling in the third world, hauling along a lot of paper books wasn't practical. Living rural, where every book had to be backpacked in.
I've stuck with it because it works for me and because I've enjoyed stretching my muscles of concentration on the screen. To me, the focus required to read an ebook from the screen is similar to the focus required to work on a program. And completly different than skimming through a web page.
The best example of this that I have right now is Real World Haskell, which I've almost finished (hurrah!) reading in a combination of paper and web editions. I was only able to stick with reading this book when I got the paper version. I use the web version for reference, or for looking for help on a challenging part of the book. For reading, it's just too much a web page; too easy to skim, or be distracted by the comments that can be attached to every paragraph, or jump off to Wikipedia.
Just as most programmers tune their development environment so that it uniquely suites them, I've put a lot of thought, trial, and error into tuning my ebook reading environment. The most important thing seemed to be getting rid of anything that interfered with focusing on the text. Since I wasn't (easily) able to use that environment for reading Real World Haskell, I wasn't able to read it from the screen.
My Nokia n810 is pretty readable and a lot lighter to carry than books. I carry a bunch of spare batteries and use 1 per book. :P
Books have to be in html though. Perl -ne 's/^$/[lt]p[gt]/; print' is useful.