This New Yorker article by Nicholson Baker about the Kindle didn't really answer the question "While this replace the book?" But it did make me want to read electronic books. Here's how:
But, fortunately, if you want to read electronic books there’s another way to go. Here’s what you do. Buy an iPod Touch (it costs seventy dollars less than the Kindle 2, even after the Kindle’s price was recently cut), or buy an iPhone, and load the free “Kindle for iPod” application onto it. Then, when you wake up at 3 A.M. and you need big, sad, well-placed words to tumble slowly into the basin of your mind, and you don’t want to wake up the person who’s in bed with you, you can reach under the pillow and find Apple’s smooth machine and click it on. It’s completely silent. Hold it a few inches from your face, with the words enlarged and the screen’s brightness slider bar slid to its lowest setting, and read for ten or fifteen minutes. Each time you need to turn the page, just move your thumb over it, as if you were getting ready to deal a card; when you do, the page will slide out of the way, and a new one will appear. After a while, your thoughts will drift off to the unused siding where the old tall weeds are, and the string of curving words will toot a mournful toot and pull ahead. You will roll to a stop. A moment later, you’ll wake and discover that you’re still holding the machine but it has turned itself off. Slide it back under the pillow. Sleep.