We expect our electronics displays to dazzle, but the Reader's is dull, and its palette is Etch A Sketch gray. There are also problems with 'ghosting,' and since it has no backlight, you need a clip-on light to read in bed. Unfortunately, the slightly reflective screen tends to bounce the beam into your eyes. The biggest problem with E Ink is that it has a very slow refresh rate—around a second to turn a page. Though that doesn't sound like much, it's quite a pregnant pause: Clicking through the Reader's menus is tedious, and page turns quickly become a bore.So it's not as good as an actual book.
The Reader works well for plain-old, front-to-back reading. As long as you don't do a lot of flipping back and forth, the device won't let you down. But it doesn't have a search function, nor will your book's index or table of contents be hyperlinked to the pages they reference. So, ironically, it's significantly easier to find information in a paper book than in its digital equivalent. Sony's e-content is also read-only: You can bookmark a page, but you can't add marginalia.
Isaac Asmimov (in an essay I can't find online) once described the perfect reading system: high definition, high contrast, portable, zero marginal energy use, stable long term memory and easily disposable. In other words, a book.