I got a Kindle reading device in July 2009, and I've been a fan ever since, although what "Kindle" means to me is evolving.
The hardware I got was the second generation of the smaller size (my wife has the current version of the same), and I can honestly say that the device itself is mostly unremarkable. It's not especially slick or nice to look at (as a device), and this is likely an obstacle for Apple loving, iPhone carrying people to enjoying the Kindle, but that very obstacle leads to one of the killer features of Kindle:
Kindle is not a device, it's a platform. I'm not the first to say so, but I feel like it's not well understood out there in the world. I have purchased dozens of eBooks from Amazon since 7/2009, and I can read any of them on my Android powered phone, on my laptop, on my PC, on the Wife's Kindle - all of the devices are registered under a common Amazon account. From each of those devices I can pull a book "from the cloud" where my archive resides on Amazon's servers, and from each of those devices I can shop for and buy new books (there continue to be a large number of "free" books available via the Amazon store, mostly classics and promotional items)
This degree of flexibility is in stark contrast to some other device / content systems out there, perhaps most notably the iTunes/iPhone/iPad universe...Apple has consistently introduced obstacles to efficiently sharing content among devices.
Reading an eBook vs a paper book changes the experience in some material ways. After reading most of the 4-Hour Body and skimming the rest, I found myself struggling to remember some details; the "search" function in the Kindle software (across devices) is an amazing feature in this situation. The ability to make notes on the text, and to then be able to view the aggregate notes for a given book in one spot is so useful...
My mom got a Kindle device for Christmas, and she offered the comment that Kindle has the potential to dramatically change the experience of high school and college...I'm not convinced that the Kindle hardware would have this affect, but I definitely see the potential for a multi-device platform to provide a real opportunity for students.
In the meantime, there is a debate out there in space about whether the iPad or the Nook or the Kindle is the best option; insofar as I have an opinion, I'm going with the Kindle platform on the device of your choice. One advantage to the keep-it-simple Kindle hardware, at least in my experience, is that you are not a finger twitch away from email, the web, YouTube, etc...I can actually zone out and read a book on my Kindle (when I use the Kindle app on my phone or PC I tend to bounce around, from book to web and so on.)