Unusually, I'm a late adopter...
Usually, I'm a sucker for gadgets, but it's only with the 4 that I've decided to finally go for an ebook reader. And it's fantastic. I don't care that it works best with Amazon books - that's who I buy most new books from anyway, and it's very quick and slick - preordered a book a couple of weeks ago, it was released today, and was automatically downloaded to the device without prompting.
There's also a Kindle 3 in our family - and it doesn't get used much. It's too big to fit into a pocket, and the keyboard is almost never used. And there's an iPad which is fantastic for web browsing and email and stuff like that, but not fun to read a book on. As a device purely for reading books and nothing else, it's perfect.
The page turn buttons are smaller, but still perfectly easy to use one-handed. No idea on battery life - I've not recharged it yet - but it's dropped one bar in a week and a half of reading for about an hour a day. So a month is certainly believeable.