I read a ton of programming books for fun (mixed with business and fiction), and spend a ton of money on amazon buying paper books, so I was naturally interested in the Kindle DX as it would save me a lot of money and space in my apartment.
Anyways, I've had mine for about 2 months now, and haven't regretted it at all. Every programming book I've purchased reads just fine, and I have had no issues what-so-ever. The only thing that kinda bugs me is that some books (I'm looking at you, pragmatic bookshelf) don't have a kindle version, however, most do.
Also, if you turn your 3G off, the kindle will run for well over a month without a recharge. I've had mine on for the past 1.25 months or so without charging, and that thing still has 25% battery left. Crazy.
Are you unable to read the (DRM-free!) MOBI versions of the PragProg books on your Kindle? (Because I can...)
Or are you just referring to being unable to purchase Kindle versions directly from the Amazon.com store?
Also, unlike the iPad, if you get the kindle you can read your kindle books on a desktop computer using the appropriate kindle app.
Tip: If you're reading PDFs on a kindle, it can be useful to open them and crop out the margins. Preview.app on OS X will do it.
I dislike the iPad for reading. At the end of the day I don't want to be looking at yet another computer screen and the Kindle's e-ink screen is so much easier on the eyes.
I played with other e-readers while I was in the process of buying mine. The Sony just didn't have what both the Kindle and Nook had behind it with their stores. The Nook had too slow of a refresh and wasn't as easy to navigate, plus the color screen was too much of a gimmick.
The only thing real books beat the Kindle on is filling a bookshelf and easily flipping through it.
If you read the book from cover to cover then it'll be great. If you want to look up specifics in the book, then it'll be great for that too thanks to the search.
On the other hand, if you want to flick through the book reading the parts that interest you then paper is still much easier to use.
As for an iPad, I can't see how it would possible be any better than a dedicated ebook reader for reading programming books. I'd stick with my Kindle.
I like my Kindle 3, but for reading I think it is only suitable for novels and plain prose. I actually use the web browser a lot. It's terrible, but it's free! (3G data, no fees or contract)
True, but you can make this work a bit better by setting up bookmarks. If a book has a table of contents that links to the chapters, that would make it easy to set up bookmarks for each chapter, that can be accessed from the menu.