Read some of these post on the Apple Support site.
Apple - Support - Discussions - Apple TV
Got mine today, hooked up and running with no problem. Loving it.
Got mine about 10 days ago. Was very easy to set-up and works perfectly as I wanted it to. I really wanted a simple way to access both our iTunes and Netflix accounts on the 50" plasma in the living room.......wirelessly.
For us, the Netflix integration alone was worth the $99. We had been accessing Netflix from our LG bluRay player but it only allowed you to play items from your instant queue. AppleTV allows full access to your account and the interface is very polished and easy to navigate.
We had an old PC since we upgraded my wife to an iMac i7 so we use that as our always on iTunes host tucked away in the office.
The second big item for me was the wireless. In our new apartment running CAT 5 to the family room would have been a PITA and buying a wireless adapter for the bluray player would have been a good chunk of the cost of the ATV so it made sense.
iTunes is the 3rd reason and it works great. So nice not to have to go to the PC and fire up iTunes and stream it via the airport express ATV replaced.
The Remote app is also very slick on iPad and iPhone although I programmed our Logitech Harmony remote to control it so I tend to use that.
Picture quality from Netflix is better than what we got through the LG bluray player and the movies run flawlessly once loaded. We use to experience numerous starts and stops while Netflix would "adjust to network conditions" not with the ATV.
Overall exactly what I wanted and worth what we paid. I'm satisfied.