I treated myself to a Kindle a couple of months ago, and I'm pleased to say that I've been enjoying it a lot. I've read just over a half-dozen books on it so far; some at home and some while traveling.
At first, the page turning buttons are a little frustrating because it is very easy to accidentally press them. This is something you train yourself not to do in pretty short order.
The screen is very clear and easy to read, and has a configurable font size to cater for the eagle eyed through to the bleary eyed. There's no back light, so you need to provide your own illumination, just as you would for a regular dead-tree book.
I've found it very easy to read. I'd read in some reviews that the visible page refresh takes a second or so when you turn a page, and that some people found that annoying. I view that as being equivalent to actually turning a page and giving your eyes a moment or so to move back up to the top left of the screen. I've started to press the "next page" button as I'm reading the last line; this is an unconscious action.
The online store integration works well; you can literally pick out a book and have it appear on the device within a minute. I find this especially appealing if it's the weekend and I don't feel like taking an hour out to drive down to a book store, but it's also good if I finish a book while I'm on the road, particularly because I don't then have to lug an extra book or two back home at the end of the trip.
The battery life is excellent if you remember to turn off the mobile antenna when you're not using it. I've been purchasing a book or two before a trip and been reading for several hours on the plane in each direction and an hour or so each night for several days on a single charge, and the battery is still only about half-way done when I arrive home.
While I was in the UK, I was unable to use the wireless antenna to access the store, but I did download a couple of books to my laptop and copied them across via USB (you can mount the kindle as a mass storage device).
My only real annoyance with the device is the page turning buttons; they're quite easy to nudge as you're settling down to read, so you have to click the button for the opposite direction to correct that.
So, in all, I'm really enjoying the device; a little pricey, perhaps, but it's the kind of thing I've been waiting for for several years--definitely way ahead of reading ebooks almost half a decade ago on my old HP iPAQ.