Many have asked in various forums for thoughts on the Kindle. Here they are in one place. I mostly got the Kindle DX for work (to read Pdf's). For that, it is passably ok. I have been able to cut down on the stacks of printouts I normally carry around. It is nice for a student to e-mail me a document, and then I can just forward his e-mail to my kindle, and be able to access it just like that. It is annoying there is no folder system (though I wrote a perl script that fakes it reasonably well). Another feature that is useful for commutes is that it can read stuff aloud, which is useful to catch up on random papers, during my long commutes. But the main annoyance is that it is quite slow. Too slow to page quickly through and the keyboard is a bit too fiddly and search too slow. It comes up when trying to find a particular table in a paper, or for paging through the couple magazines I subscribe to that offer pdf versions.
I await new versions with hopefully better contrast, faster load times, touch screen (like the Sony version), and even color, and better keyboard.
It is still pretty great for its main purpose, which is reading novels. For the Kindle formatting books, the contrast is not a problem, the screen is definitely easier to read that a computer screen, and it is so nice to be able to impulse buy books, like iphone apps, and have them right away. Amazon claims that of books that have kindle versions, 40% of its sales are electronic, which I can believe. Formatting is still a bit off, and annoying you can't page through easily, but generally fine for just reading.
Oh, and battery life is awesome. It goes for weeks between charges.
Bottom line, I wouldn't get it yet, I'd wait for a newer version given its hefty price tag. But I have no regrets given it came out of my research budget.