Living in the unprivileged every-country-outside-of-America, I can't get my hands on an Amazon Kindle Fire, but I'm enjoying reading the reviews. Engadget has a typically thorough review up, which boils down to this:
It's physically tough, remarkably affordable, presents the best integration of content digital acquisition, and can't hope to compete with other better tablets.
In a word: Amazon. This is exactly the device Amazon would release, and I commend them for playing to who they are, rather than just delivering an iPad knock-off. Amazon's in this game for the long-haul, and this looks like a fantastic first entry. They've addressed the UI issue with aplomb, but I'd still like to see something creative with a color e-ink display down the road.