I have the earlier ATH-ANC7 NC headphones. I can't really tell you if the sound is truly superb or not since I don't have anything to compare them to. Yeah they sound great, but I only have cheap earbuds to compare them to.
I can let you know about the noise cancellation though. The noise cancelling features are really amazing. It's especially good at neutralizing midrange sounds like people talking. About the only thing that I've found able to challenge the noise cancellation are short sharp percussive sounds like coughs and it dulls those noises to a minimum.
My only complaint is that it's hard to wear these as long as I'd like because the fit is snug and your ears get uncomfortably warm after 30 to 45 minutes. I don't know if you'll be able to avoid this with other headphones though. Also, the snug fit sometimes gives me headaches, but that's probably just me since I have this problem on almost all headphones that are fine for other people.
If these are anything like my ATH-ANC7's, then you'll also want to be aware that the noise neutralizing qualities of these headphones are one way only. With the volume turned up only halfway on an iPhone it becomes very hard to hear ambient noises and you get the impression that you're in a sound proof cocoon. Anyone else within earshot of you won't have the same experience. These sound surprisingly loud to other people in the room. If you're using these to be considerate at work, it won't work if you want your tunes loud.
They don't need to be that loud with these, but you'll be sharing your music if you like it loud.