They're computers, with glass screens, which makes them candidates for breakage. I didn't drop either one, but clumsy me is sure to crack the screen sooner rather than later. And they'll be difficult to use in my favorite reading spot, the beach. And I'd caution my wife from reading one in the tub as well. Neither of the two other electronic books planned for later this year, from Librius or Everybook will solve those problems.
Electronic Books make sense for carrying around lots of manuals, or for a college student.
I can imagine a kind of electronic book that contains all the texts for a semester, along with notetaking ability. Reference works, like a dictionary, thesaurus and encyclopedia would also be good in this format. But I'm still betting that paper books will be around for a long time. Paper is cheap, easy to read, and is surprisingly durable. Paper has another edge over the electronic too.