In October 2010, I broke down and bought a Kindle 3 (with the chiclet keyboard). That is now four years ago. While I do not do all my reading on it—I like real books better in many ways, and I have a Kindle application on all my other electronic devices—I have regularly used this version of the Kindle, reading regularly some journals and papers (like The Atlantic and the Times Literary Supplement) on it, as well as some books that I did not buy as hard copy. There isn't a week in which it does not get some use.
I have never regretted buying the Kindle 3. Nor have I ever felt the need to update it. Though I have played with the Nook, I have given the ones I had (because of Barnes & Noble gift cards) to relatives. The Kindle 3 is a device that just works. I can easily see myself using it for another four or even eight years. There are not may electronic devices of which I could say this.