Well I picked the 3rd generation Apple TV this afternoon & I have to say, I'm very impressed! I'm typing this just now mirroring my iPhone on my livingroom TV & it's really clear although it doesn't show as full screen (black borders at top & bottom. It nothing major.)
Tried iplayer, 4od, 5 on demand & ITV player, they work no problem but Sky Go isn't compatible. Tune In Radio app works fine too & large screen Angry Birds through surround sound is awesome.
iTunes integration is fantastic & showing the cover art on screen is a nice touch.
Netflix & YouTube apps included are fine too.
Overall, a great piece of kit