I was on initially on the fence about this, I have been a book reader since I could start reading and didn't think it would make a difference. It does. The Kindle is not only easy to use and extremely convenient, it is fast, holds over 200 books and book prices are cheaper than if you bought them in the store. You can also subscribe to newspapers, blogs and magazines, download sample blurbs from books and easily browse new releases and best sellers. The only downside is there is no light source or backlight, so just like with regular books, you need a book light or lamp to read. Also, I like to browse the Amazon book selection by price (there are a ton of free and under $1 Kindle books) and I can only do so on their web site (as far as I can tell).
I love it, I carry it in my purse, so if I'm stuck waiting in line, in a doctors office, restaurant, movie theater, I have it ready to go. The battery seems to hold a charge for a long time, I haven't clocked it, but I've never run out of battery. As of this writing, they have released a Kindle 2, which is thinner and lighter, so you may be able to get deals on the original Kindle for people looking to upgrade, either one is well worth the investment. Plus, think of all the trees you'll be saving :)
Full disclosure, if you click on the links and buy from Amazon, I get a tiny commission. Thank you!