Every time this comes up, I sympathize with the physical book lovers. I agree with the opinion that a large part of the joy of reading comes from the tactility of a physical book. I love well-made, high-quality paper. I also miss, with e-books, the ability to browse through a book, picking out favorite passages. Physical books truly engage more of the senses than e-books.
That said, when I choose "what to read next", and browse my bookshelf of unread books, and look at my list of unread e-books, I overwhelmingly choose to read an e-book next. I wish I could define why. I don't miss the kinesthetic pleasure of a physical book. Or, cradling the Sony Reader in it's nice leather case, with it's elegant, sleek design, provides a good enough analog that there is no barrier to sinking into the story, which, when all is said and done, is the point.