I have had a Kindle for several years. I purchased mine while it was still expensive. I gave one to my wife for Christmas. It only cost $139. Even at the higher price, it was a value for me. I have poor vision and I'm able to enlarge the text making it much easier to read. It also has a built in text to speech application for books that the publisher has not disabled.
The eInk is very clear and high contrast. You can read it for much longer periods of time that you can read a computer display. The newer version my wife has it noticeably better than mine in a side to side comparison. I still like the larger size and button placement on mine, so I will use it until it fails.
Another feature I like is the small size and reduce weight when compared to a physical book. Even with paperbacks, it is much lighter. There is simply no comparison with with a hardback. With my poor vision, I have to hold reading material fairly close to my face, so for me, the weight is very significant.
As someone mentioned, you can obtain Kindle applications for most computer formats, PC, Mac, most smart phones, and tablet PCs. They are very handy. When I am stuck somewhere with only my iPhone, I still read all of my Kindle books. You can download any of the books you have purchased to any device you are reading from. I have hundreds of books including reference books. I can obtain any of them in a short period of time just about wherever I am at.
I also have a subscription to one daily newspaper and a couple of magazines. The ones that I read are very well priced.
The only negative for me is reading textbooks and technical material. I still prefer having the real book so I can easily scribble in the margins. You can easily add notes to the Kindle as well, so it shouldn't be an issue. But I still prefer paper in that situation.
For me, the Kindle system is still the best. I am an avid reader and check out the new models whenever they become available. I was at Barnes & Noble this afternoon. I have been asked to tutor a kid at the local high school in Geometry and needed a reference. The new color Nook looks very nice but it is back lit.
BTW, you can now get games and puzzles for the Kindle. I have chess, soduku, NY Times crossword puzzles, and a couple of interactive mystery novels that are enjoyable.
I hope this helped, Debbie and I really like our Kindles, our reading habits make them worth the cost.
Jeff