Macintouch has the best and most positive Amazon Kindle Review I've read.
I think Paul Krugman is also a fan.
Interesting comment -- the author felt the ideal audience is people who are running out of book shelf space, rather than people who read books then give them away. (We're more the latter.)
On the other hand the Kindle is Windows centric. The Audible support requires a Winbox.
I'm impressed. I was skeptical about the Kindle at launch time, but it does look like a real success. (You were right Andrew!).
I'll keep an eye out for Kindle 2.0 -- and for Apple's rumored challenger. There are still a ways to go before it passes the four tests.