I just restarted my Netflix subscription to test out the performance on Apple TV. I canceled Netflix 2 months ago when this chain only had 40,000 views on it (now it's 113,000) and 2 updates ago. I also got a new Blu player that has the Netflix app built in so I can do a side-by-side streaming comparison.
My details:
Los Angeles, CA
Time Warner Cable
100MB/s turbo-ultra service (waaaaay faster than the standard 15MB service)
ATV & BD Player = wifi, not hardwired
ATV3 performance: I used the "Example Short 23.976" which started off at something like 340x260. Every 10 seconds or so it increased, and eventually got up to 1280 x 720 (which isn't SuperHD). I left it run for 2 minutes, but it never got better than that -- but still, that's better than the resolution I was getting when I canceled the service.
BD Netflix performance: same as above, but after about a minute it eventually worked up to SuperHD which I think was 1920x1080.
The ATV3 was still a bit slower, but at least now I have an alernative.
Kirby