E-Books still aren't there yet. When an E-Book as as convenient, as cheap, and as trouble free as real books, then we'll see e-books take off. But I think they've still got a way to go. Prices need to come down, the devices themselves need to get better (more durable, longer battery life, cheaper) and the software inside them needs to get much better.
Speaking only from owning a Kindle, the limitations on display imposed by are sometimes infuriating: Limited type choices, no ragged right, an orgamizational system which doesn't scale past 100mb of material, let alone the two gigs that comes onboard, (Why people moan that the kindle is not expandable I'll never understand. Aside from a wikipedia dump, who needs two gigs of text on the go!). PDF Support needs vast improvements (why, god why do you let me zoom, but only to the scales you chose for me... which are always way too wide or ten letters too narrow on academic papers?)
Annotations for academic work are important, and on the impotent keyboard they give you on the kindle, good luck. HIghlighting is slightly better, but still painful.
Having ranted though, I have to say, I still love my kindle, if for no other reason than receiving my news paper every morning electronically, combined with Instapaper for long articles.
The devices have amazing possibility, but until they improve, they won't kill the book.