HE'S GOT A POINT: Why the Smart Reading Device of the Future May Be … Paper.
I read a lot on the Kindle and, while I love it, it does lack the 'visual' cues that you get on paper: shape, thickness, size, typeface. You don't have the almost subconscious information of how much you're read just by holding the book and feeling how many pages are on each side. As the article says, this gives a sort of 'mental scaffolding' that helps you remember (on the other hand, the Kindle is much easier to hold than a book, especially softcovers and particularly when you're beginning of finishing it). But it's true: in some way all books 'look the same' on the Kindle, which in some ways makes them less memorable.