We got a few of these around the office yesterday and I spent a few minutes playing with it. As you would expect with Apple products it was easy to get going and use and much of the content looked good on a normal (4:3) TV. I read several reviews that mentioned it wouldn’t work with non-widescreen TV’s but it does just fine, although you lose a bit of screen size.
I am not sure I would buy one for home just yet, but once they get better integration with content directly from the web it may be worth a purchase. That and making better use of the USB port so I can actually keep most (or all) of my library local. You can certainly imagine buying (or renting) movies via iTunes that then download to the Apple TV for playing then or later. Just as downloading services continue to improve I expect Apple could jump in a take most of that market.
I haven’t made the Amazon Unbox / TiVo connection at home just yet but this is a space I think Apple would be wise to get into as well.