Excerpt: The specification claims that it blocks out 99% of noise. It makes your environment very quiet, but enough to hear the external sound just a bit. Opinion: I bought this headphone for noise cancellation, so I would not recommend this for audio freaks or audiophiles. But indeed, it is a perfect noise cancellation headphone. I would highly recommend this headphone if you are a commuter irritated by the outside environment.
Summary: Even at first glance, it can be glaringly obvious that Head-fi in general isn't a fan of Active Noise Canceling Cans, and there are valid reasons for this; for one, the active NC module is prone to creating noise and distortion in sound on its own, and for two, there simply aren't too many good ones around.
Pros: Great noise cancelling ability, works without NC active, good sound (considering it's a NC can), comfortable, great value
Cons: Has typical active NC headphone limitations, and as such there will still be some compromise in SQ