First off, if you get the uVerse u200 package or better, the DVR is free, so you would only save if you ordered u100.
The Apple TV isn't a video capture device - it is a playback device. Think of it like a giant iPod. It plays back iTunes compatible music or video but on your TV instead of your headphones.
For me, THE reason to get an Apple TV is to play back compatible Video on your TV instead of your computer - without using your computer at all.
The Apple TV is a good solution for:
Renting or purchasing a movie from the iTunes store and playing it back on your TV.
Downloading a Video podcast and playing it back on your TV.
Playing music from your iTunes library on your TV/Stereo
It is NOT a solution for:
Watching video's on Hulu or other streaming sites (except for youtube)
Watching videos in NON-COMPATIBLE formats
Recording Videos
For me, I watch a number of Video podcasts, and rent movies from the iTunes store, and I want to see those on my TV - without having to plug in my computer into my TV. For that it is great.
I use my uVerse DVR for recording and playing back regular TV.
To me they are complimentary devices - one does not replace the other.
Now, if we can get Safari to run on the Apple TV (without a hack), and you can watch Hulu and other streaming sites, then you have a whole different ball game.
If you are interested in creating your own DVR, then a Mac Mini would be a better choice, with something like the Elgato TV solutions. just keep in mind that nothing will be able to record uVerse very easily, except for the DVR. Your only options for recording uVerse are using the composite outputs, which are cropped or disconnected when you use the other outputs for your TV. It's really not practical at all.