For general reading like novels, history, etc I love my Nook. It is much more portable and handy and if I want to switch from one book to another it is a breeze.
Now, for textbooks and technical material (I am an IT professor) it is not so great and for those I prefer my traditional hard/soft bound books. I’ve had students who have tried etexts and most were not very happy with the usability.
The page turning time needs to be faster and the bookmarking method needs to be better. I remember times when I had every finger on one hand marking a page I was referring to, plus a pen, a pencil and another smaller book used as an emergency bookmark. Maybe a full PC screen with windows to multiple locations in the book would help too.