I wouldn't buy one. I completely get the idea of having an e-reader, but I don't like being locked in to specific file formats or proprietary hardware which might restrict how I use it.
When I used to travel to work by train (5 years ago) I used to read books on my pda. There are 33,000 available free from
Project Gutenberg, plus many more from commercial sites.
I found it really handy as it meant that I always had my book in my pocket, if I had 5 minutes to kill while waiting in a queue or something. While I still prefer to read from paper, the convenience of 'always with me' meant that most of my book-reading was in this form. I read pretty much the complete works of Trollope, quite a bit of Dickens and a lot more on my pda.
This approach worked better for me than a proprietary device like a Kindle would have done (if it had been invented then!) because I read very quickly and want to be able to control how the screen set-up looks. I much preferred to have books as text files so I could choose my own font and avoid large borders. With pda e-reader software or pdfs I found that the pages did not have enough text on them to enable me to read at normal speed. The Kindle software may give more options than pda e-readers, but it won't give more than a text file.
The Kindle certainly has its customer segment (as both its sales and the messages on here prove) but if you own a pda already and have the modest level of IT / internet searching skills needed to track down, download and convert text files, you don't need one to access the benefits.