There should not just be buttons for page-turning, but great buttons. Buttons exquisitely designed and engineered to be perfectly placed and delightfully clickable. The problem with using the touchscreen to turn pages is that you have to move your thumb, from the bezel to the display and then back to the bezel after tapping, each time. With page-turning buttons on the bezel, like on the old pre-touchscreen Kindles, you never had to move your thumbs while reading. Not having to move your thumbs is one way a dedicated e-reader could hold an advantage over tablets like the iPad and Kindle Fire — a missed opportunity here. It’s a little thing, but as always, it’s the details that matter.
From Gruber’s review of the Kindle Paperwhite. I agree, this is my one complaint of an otherwise excellent device that’s leaps and bounds better than my erstwhile 2nd-gen Kindle.