The astronomical price tag is all that stops this fantastic product from getting 5 stars. I was fortunate enough to be given them as a birthday present by a group of friends, otherwise I could never have afforded them. Apart from the cost, they are, in my view, pretty much flawless. They are very comfortable and the headphones themselves reduce exterior sound by around 1/3. When switched on, they do exactly what they should; they reduce noise, not sound. You can still hear people speak and ordinary sounds appear dulled, but still audible. However, all the noise (in the true sense of the word - as in white noise) is cancelled out. This allows you to listen to your music at volumes far quieter than with conventional headphones, hence these are a lifesaver on a plane, in the car, or in any crowded or loud surrounding. Sound quality is exemplary; when compared to my standard "earbud" style headphones, well, there is no comparison. Bass tones are rich and deep but never forced and the higher notes are crystal clear but never tinny. Battery life seems close to the claimed 35 hours, in two months I have used only 4 AAA batteries. The headphones breathe well, with specialised ventilation so ears don't get too hot, even in warm conditions. The case is sturdy and keeps the headphones clean and safe, it even has it's own ventilation to allow the headphones to dry if replaced when slightly damp. It also has a place to store spare batteries so you need not be caught short. I can find only two minor flaws; the first is the fact that, without batteries, these headphone will not function at all, requiring a regular set to be carried at all times in case of sudden power loss (however, a set of earbud style headphones fit easily in the case as a backup). The second flaw is a strange bumping noise experienced when walking with a heavy step, the headphones appear to pick up the jolt created by your feet striking the ground and amplify it hugely. When running it is unbearable. Aside from these small criticisms, I am delighted with these headphones, in my opinion, they provide a truly wonderful listening experience.