I have a Kindle and I wouldn't worry much about the DRM. Although it's true that the books you buy from Amazon will likely be locked, the device does not in anyway require that Amazon be your only source for books. You can send essentially anything to it, either by transferring it from your computer via USB or using their (fee-based) email conversion service. This latter service will convert most ebook formats and automatically download it to your Kindle via 3G. They also offer a free conversion service, but you'll have to transfer the resulting document via USB.
Personally, I use Calibre as an ebook manager and it automatically converts pretty much anything I can throw at it into a format compatible with the Kindle and then automatically downloads it to the device. With all of the classic books available from Project Gutenberg, as well as various other book sources, I've yet to purchase anything from Amazon directly.
If anyone is waffling over buying one, I can only heartily recommend it. I was dubious at first, but I'd say the experience is even better then an actual book (that wonderful book smell aside). The display really is fairly amazing. Plus, with the global wireless, you can access Wikipedia for free from almost anywhere in the world. In some countries, you can even get full, free web access (a nice feature on my recent trip back home to SF). With the 3g feature disabled, the bloody thing also seems to have near infinite battery life. I read for at least an hour or more a day and I haven't changed the thing in well over a month. It's a great device.