TOD:
I love my Kindle! I also love books. But I don't have to own a hardcopy of every single book that I want to read--my bookshelves are already packed and overflowing. The Kindle can hold thousands of books, plus anything I purchase through the Kindle bookstore is stored in my Amazon Digital Locker (or whatever it's called) and I can download them whenever I need to. If I come across a book elsewhere that's in pdf form, I can e-mail it to Amazon and they will convert it to the Kindle format.
The Kindle is lightweight, so reading something like that last Stephen King book was not also a weightlifting experience. And the screen is completely readable in all kinds of light. I regularly read from my Kindle on the beach during the summer. (I do wish that it had a back light for bedtime reading, but it seems they are concerned with battery life. I get around this by using a clip-on light.) The unit is also durable--I've dropped it a number of times with no ill effect.
I also still like shopping in bookstores and browsing and buying--nothing will ever replace that experience. But I also have immediate access to hundreds of thousands of titles through the Kindle bookstore through the device itself, a healthy portion of which are free. Back in November, I had a hankerin' to read Dickens' GRRREAT EXPECTATIONS; I had it on my Kindle in minutes.
An added feature is internet access. While the browser is not high-resolution, it's serviceable enough to use to look up information if you need it right away. And there is no monthly fee for this access.
There is also a built-in dictionary that can be accessed while reading. If you come up against a word and you need to look it up, you just highlight it, hit a few buttons and you have a definition.
Up till the recent brouhaha Amazon had with Macmillan, pricing was also an advantage--all new books had the top price of just $9.99. I'm not sure what the future holds in that area, though. Also, not every book is available, though from what I understand, a ton of back-catalog books are going to sold on the Kindle bookstore in the coming year. I'm still waiting for THE WITCHES OF EASTWICK.