It's based around a new way of interacting with your device and as you'll have noticed, there has been no mention of navigation buttons in the sections on design or hardware. (pocket-lint.com)
It also gives you a high degree of sensitivity for interacting with your device via a stylus. (goodereader.com)
Many of the other higher priced e-readers are not touchscreen and do not really allow you to interact with the device in terms of taking notes and highlighting. (goodereader.com)