It's out. It's ugly. And its reception has been somewhat luke-warm. Then again, when the first generation iPod came out, people laughed, spat and declared it an abject failure. Here's some ramblings from the bloggerheads:

Mr. Pilgrim:

You may not sell, rent, lease, distribute, broadcast, sublicense or otherwise assign any rights to the Digital Content or any portion of it to any third party, and you may not remove any proprietary notices or labels on the Digital Content. In addition, you may not, and you will not encourage, assist or authorize any other person to, bypass, modify, defeat or circumvent security features that protect the Digital Content.

Mr. Greenfield:

Unless something comes along to radically reorient my thinking, I’m willing to bet Chris Heathcote has nailed it in eighteen words: “Kindle is what happens when a non-cool company attempts to do a closed service: a car crash.”

Mr. Godin:

The challenge that my hero Jeff Bezos has is that if he's really really lucky, he'll sell a million of these things in a year. And that means that at $10 a book, you need to have significant market share to make an impact. The Sony reader has been out for months and it has sold, perhaps, a few thousand units.

Mr. The Reader

Mr. Fireball

So the Kindle proposition is this: You pay for downloadable books that can’t be printed, can’t be shared, and can’t be displayed on any device other than Amazon’s own $400 reader — and whether they’re readable at all in the future is solely at Amazon’s discretion. That’s no way to build a library.

Mr. Kawasaki

I have used it and if someone gave me a choice of receiving an iPhone or a Kindle, I’d pick the Kindle.

Updates:

Here's a couple sources with more specific details on the Kindle:
15 Things I Just Learned About the Amazon Kindle (Boing Boing)
Many Details About The Kindle (Engadget)