There are three things I've found where paper books are still superior to ebooks, aside from DRM and file format concerns:
1. unusual dimensions, such as coffee table books
3. locating a particular passage when you don't remember the exact words
One virtue of printed books is that they can be printed in whatever size and shape you desire. No matter how well designed an ebook is, it can't replicate the same experience.
Illustrations and charts are rather hit-or-miss with ebooks. Some titles have illustrations are done well, with scalable or sufficiently high resolution pictures to let you see them clearly when zoomed in on a small screen. Some other titles may as well not include the pictures because they are so blurry on the screen even at normal size.
Thirdly, have you ever remembered more or less where to find some information in a physical book (i.e. how far to turn the pages) but you can't come up with the right search terms? Current ebook technology can't help as much with such fuzzy situations. I think I read an article somewhere about the brain remembering physical locations better too than abstract book locations.
Despite these shortcomings, ebooks satisfy most of my needs. Ebooks may not be for everyone but they suit me just fine.