I'm reading the WSJ on it. Basics are great. You can read it anywhere, and the lightness and improved controls are a big part of the experience. So now to the gripes:
1. It's too easy to miss stories by mistake with the Kindle/WSJ interface; not a big deal but distracting.
2. How come the Kindle store won't show me my regular Amazon Wish List? That's where I put the books I think I might want some day, and I use it to browse when I'm in the market for another book. This thing makes me start all over, or only read it with my web page open in front of me.
3. The first book I tried to buy (Charlie Duelfer's book on Iraq) is in print but not available on Kindle.
4. The wireless service should shut down automatically unless I ask for the store, or Amazon sends a message that there's a subscription to download. Kindle could wake up every few hours to check. Why burn battery unnecessarily?
4. Would it have killed them to make Wifi available? That would allow the machine to operate outside the US.
5. I worry I'll drop it. Amazon should have included some sort of protection, especially if the screen is as fragile as I've heard.