I have never seen a Kindle (DX or otherwise), but they have E-Readers on display at Borders Books in my area. They are nice looking, and they are just as f0dder described - flicker free and easy to read, but very slow to change pages.
I find it funny that so many people complain that there is no backlight. DUH, that is the point. If E-ink were backlit, you would start to run into the same problems as LCD screens. Why get E-ink then backlight it anyway? If you want to do that, just get an iPod Touch or similar and use that. They are about the same price and much more versatile.
My big problem with them is economic more than anything else. Why should I pay over $300 more for an electronic reader, then pay the same price for the data, then when I loose it/break it/decide I want a newer device I loose the book. Also, with systems that push and/or keep your files (like Amazon), they can also remove them permanently. When I buy an e-book, I want the entire file, and I want it where I can access and move it on my own computer and my backup scheme, not where Amazon can say "Oh, we weren't allowed to sell that." and boom, all I have left is a credit for another book to download. What if that was the only book on the entire system I wanted! That is just wrong. They should do their due diligence before the sale, and if they made the mistake, they should pay the author for their mistake - Not me paying by loosing access! At the very least, they should refund the money instead of just providing credit.
As to the original question, I only use it a lot when I am in class. I think I have maybe ran 500 pages through my laser since I graduated with my MBA. I am sure I will use it alot again with my Doctoral studies...
Of course at work, I run the Printroom, so yes, we use it extensively there. In fact I run 3 of them with an average output of somewhere around 40,000 pages a day when run at full capacity. Of course we rarely run that much. Usually closer to about 5,000 pages a day on average.