They're nice to have, although there's plenty of room for improvement.
Much easier on the eyes than an LCD screen; I can actually read a book with one. But not so great for texts with footnotes, graphs, equations -- let alone appendices. To compensate for that, I keep the pdf up on an LCD screen to refer to when needed ...
I much prefer reading a paper book, though -- all sorts of pleasures are absent from a Kindle, from sunlight striking the page to flipping back and forth inside the text -- you can't flip an a ebook. The pace of reading is different.
It's interesting to note that many people that used not to are reading now because they have a reading gadget -- books were always alien to them, but ebooks are somehow different. (I've heard it said, too, that the stock of schlock is on the rise because now nobody can judge you by the cover of the book you're reading -- who's to know whether you're slurping down a Sidney Sheldon or reading something high-brow and intellectual like John Grisham. New facial expressions are probably appearing at poolsides around the planet).
