I bought my first kindle about two months ago. I don't use it daily, but when I do, I am impressed. One day I was riding on a train through Korea reading my Kindle. About halfway through the 10th tunnel, I realized how well-lit it is. Normally, I had to pause and wait until we passed through the tunnel to continue reading. My Kindle was perfectly lit with the sun shining in the window and when under a big mountain.
There are two things that I like about my Kindle that I did not know about until I bought it.
1) I love the social bookmark function. it is great for previewing a book. It is interesting to see what hoards of other people felt was worthy to bookmark.
2) I am not certain if they are actually doing this one. I think that my Kindle is learning from me based on both my Amazon book browsing history as well as what I search for on Audible.com (owned by Amazon) It seems like the screen saver suggestions are getting more tailored for me. Again, I am not certain if this is true.