Here are two reviews of ebooks from Jacob Nielsen.
http://www.useit.com/alertbox/980726.html
1998
"Electronic text should not mimic the old medium and its linear ways. Page turning remains a bad interface, even when it can be done more conveniently than by clicking the mouse on a "next page" button. It is an insufficient goal to make computerized text as fast as print: we need to improve on the past, not simply match it."
http://www.useit.com/alertbox/kindle...ty-review.html
2008
"Amazon's new e-book reader offers print-level readability and shines for reading fiction, but it has awkward interaction design and poor support for non-linear content."