I’ve just finished reading an eBook (Cory Doctorow’s Down and out in the magic kingdom) on the Kindle, all in all a very pleasant experience.
The device has a six-inch electronic paper display, which is as good as electronic paper displays are (personally I think they’re good). It has a number of page-navigation buttons, a thumbwheel and qwerty keyboard with some function keys (such as font-size key). The navigational controls are OK (a little sensitive for some), and I especially like the silver cursor activated by the thumbwheel (most amusing).
The device reads titles distributed by Amazon via its WiFi, and free eBooks downloaded from the Net (transfer via USB). It supports documents and audio files (it has audio playback too) in the following formats: Amazon’s own AZW format, Mobipocket without DRM, plain text, MP3 and Audible.