Although I was an early adopter of the original Kindle, I've eagerly anticipated Amazon's Kindle DX. The original device was, and is, well-suited for light reading of non-serious material, but its small screen size and lack of PDF support made it mostly a recreational device. I quickly realized that any serious technical book still worked better in physical form. That, combined with the original Kindle's inability to handle PDFs (Adobe Portable Document-format files, a rendering of a document's printed image via Adobe Acrobat and other converters) in a usable form (the conversion left a lot to be desired), made me look at other e-readers, particularly the iLiad iRex Digital Reader 1000-series. Unfortunately, the iRex 1000 ereader, at above $1000, was still a work-in-progress, with serious deficiencies in terms of functionality and reliability, and I didn't want to be an alpha tester of a device that might never be finished. Amazon's announcement of the large-format Kindle DX with native PDF support seemed like the answer... so I plunked down the money for a DX and the Amazon case and got on the waiting list.
Why would you want native PDF support? The small Kindles support PDF files via translation; you send a PDF document to Amazon and they convert it to the Kindle's AZW format and send it back to you, either to your desktop email account (free) or directly to your Kindle ($0.10 per document). However, if your document is anything more than simple text, formatting and imagery are mangled. What you get is readable but not nearly as readable as a Kindle document that was specifically prepared for the device. This is an inherent restriction caused by the difference between a document file structure that is meant to preserve formatting (PDF) and one that is meant to allow for text flow despite screen or font size concerns (AZW). The result was that you couldn't practically use either the original or 2nd gen Kindles for reading even reasonably complex PDF documents. Having an integral native PDF reader on the new Kindle DX (as seen to the left) solves this problem and opens up a HUGE world of documents to the Kindle owner.
I've had the Kindle DX for about a day now, and it's everything I was looking for. PDFs render beautifully, not like they did on the original (the same PDF on the original Kindle, at right) and Kindle AZW documents render even better than they did on the original Kindle due to the larger screen size and 16-tone grey scale capability. The large screen really elevates the new DX into something more than a convenient device for light reading. The Kindle DX shows the true utility of an electronic reader for the first time. It's what the Kindle should have been from the start.
What has improved? Performance is better, particularly the screen refresh rate. The new button design means not turning pages accidentally anymore (although I wish they'd kept buttons on both sides of the device for us left-handers). I don't like not having an SD card slot on the device, nor do I like not being able to change the battery without sending the device back to Amazon. Being able to turn the Whispernet modem on and off via software (menu item) is scads better than having to move a switch. The web browser's 'desktop' mode makes the browser very usable, especially when combined with the rotation feature. Speaking of rotation, the ability to rotate the device and view documents in either landscape or portrait mode is KILLER. Text-to-speech works well, but I have yet to try it for actually 'reading' (listening to) a document while doing something else, e.g., driving, to see if it is really useful or just a checklist feature. The Amazon cover (extra charge) is WAY above the original Kindle's flimsy cover; it actually holds the device securely, protects the screen, yet is easy to open (beware of the magnetic latch around external hard drives or near the bottom of your laptop).
Okay, so now I have two Kindles. My wife asked me why I need two, a good question. My answer is, the small Kindles are great for light reading... the latest fiction novel, public-domain classics, etc., but they're useless for PDFs or more serious reading such as technical books because the screen size is too small and images, formulas, etc., don't display well. The Kindle DX is great for any type of reading and shines with PDFs and more serious books, yet it is considerably heavier than the original Kindle (I'd say twice as heavy, if not more so) and not as convenient to stuff in a carry-on bag. I've already moved all of the technical books I own over to the DX, as well as many PDF documents. I had decided to not buy any serious books for my Kindle, using it only for light reading... but the new Kindle DX has changed my mind. The experience of reading a technical book is as good or better than the physical book, and that is something that could not be said about the smaller Kindles.
If I had to own just one electronic reading device, the choice is obvious: the Kindle DX. Amazon has gotten it right; the Kindle DX finally fulfills the 'book' paradigm in an electronic device.