Opinions on "Noise Cancelling Headphones"?

Has anyone ever used any of the new headphones for editing or location?

I have a set of old Sony studio types, but the ear pieces are disentigrating, and I saw the Bose and a few others of these Noise Cancelling ones.

Would using these effect the sound I hear from my Avid (Xpro 4.6 Mojo) or Pro Tools, effecting the audio? Or is it like they say, it only cancels the outside noise?

Just looking for a few opinions before I spend a couple of bills.

Thanks!