I've had the smaller international Kindle for a few weeks now, most recently while on holiday. While the iPad is a wonderful reader, particularly for indoor use, there is definitely a place for the Kindle.
The Kindle is lighter and thinner and, being an eInk display, just gets easier to read as the ambient light gets brighter. (Below is a view of the screen in direct sunlight).
Wireless broadband is built in. Here in Australia it uses Telstra's network, there is no contract, no fees and it mostly works very well. At any time, you can turn wireless on, browse the Amazon Kindle store (of some 500,000 books), purchase something and within a minute or two it is on your home screen.
This can be addictive, particularly when there are titles for one or two dollars.
The device can also use Wifi which is faster. At the moment there is no charge for the 3G wireless delivery of books, the cost is built-in to the cover price, and there is an "experimental" web browser, WebKit based, that also currently gets this free bandwidth.
The web browser is usable but not pleasant. The screen doesn't have enough speed or pixels to make it all come together, but if you're desperate for the news it's workable. The arrow pad lets you move a cursor around the screen from link to link and there's a magnify option. I've been able to use gMail and Google News but even a phone is better choice if available.
I'm running software version 3.0.2 and so far I've had a few crashes or hangs. Mostly either in the web browser or while marking text in the reader. On one occasion I left it in my bag charged, asleep, and next day found it completely flat. My guess is that as wireless was on it somehow drained itself trying to reach a basestation in a bad coverage location.
These days I leave wireless off and just turn it on to purchase books.
As well as getting books directly through the built-in store you can plug the device into a computer, where it mounts as a disk, and simply drag titles in .TXT or .MOBI format over to it where they join the rest of the list. I think there was a bit over 3GB free when new and now it's 2.5GB despite the fact that I have 760 books in mine now.
Many of the computer books I buy from O'Reilly publishing. One great thing about O'Reilly is that once you buy a book you can download it in many different formats including ePub for the iPad and .mobi for Kindle.
As there is a Kindle application for iPad, books I buy from Amazon can also be read on the iPad.
I've owned Sony readers and played with all the others I've encountered in stores and the Kindle is the best beside my iPad.
Australian electronic book scandal
What is the story with buying electronic books in Australia? The range is much smaller and the prices are higher. Mr who?, break down this wall!