- Because e-ink is the closest thing to real paper.
- It's small but it holds thousands books, which makes mobilereading extremely convenient. *
- And of course the battery lives on while tablet needs charging everyday.
* Edited to add that when I bought it, I did intend to "bring it everywhere" as some people here do. But after 2 broken screens, I learned to err on the safe side and now I leave it home, in thick cover, on my desk on top of everything else
I can't read in public, anyway. It's just too distracting.