What I like:
Small size - easy to hide in my entertainment center!
Matte black - no shiny reflective surface, no shiny apple logo; very discrete
Power supply - only 6watts power usage? that's awesome. no need for an external brick power supply? even better!
HDMI - a blessing and also a curse; see below
Price - $99 makes it one of the cheaper alternatives for movies
Interface - simple and easy to navigate, very similar to front row for macbooks and imacs.
Streaming from PC - sweet; I've got a ton of photos, video, and music ;)
What I dislike:
HDMI - no 1080p, only 720p support. Sure it's HD, but it's not 1080p HD.
Apple A4 chip - they're sticking this thing into almost all the devices, from iPhone4 to iPod touch, iPad and now this. C'mon; get a faster chip that can handle the 1080p! Bump the specs, bump the price, charge a bit more for 1080p!
No storage - streaming only? what if my internet dies? I can't save any of my rentals for a while?
No applications - no pandora? hulu? only ABC and FOX? Needs more variety and selection; netflix doesn't even offer every movie to be streamed at HD quality.
Remote - C'mon; you can do better than that.
Overall, I think the Apple TV is a great product. Decent price, great for someone who isn't too crazy about quality of what they're watching, and just wants the ease of plug and play. But for us 1080p, video-hoarding, technogeeks, this probably won't cut it.