I bought a set of these headphones in August 2005 when they cost a good deal more than you can buy them for now (£125 to be exact). Once I got to used to the rather cumbersome way they should be inserted into the ear and also found the right size and, more importantly, type of rubber ear piece to use (I found the softer rubber tended to get stuck in my ear if one wore a size that fitted snugly) I found them comfortable and the sound was hugely better than the Sony ear phones I had before. For high noise environments, such as aircraft, they are still good, but they do not come into the same league of noise cancelling ability of the high quality over-ear phones such as can be had from Seinnhauser (sorry not sure about spelling) or especially Bose. I prefer inner ear phones for general use but on aircrfat and such like they do not, in my view, really do the job. For high quality sound in normal environments, however, they are truly great.
However, after three years use, the casing of one of the phones has snapped near the end. They are patently not very robust and I would not buy another pair for this reason. For such an expensive pair of headphones I would expect them to last a good deal longer than 3 years. My usage was not heavy. I used them when travelling by train or plane which is perhaps 8 to 12 times per year, for a two week period in hospital in 2005 and otherwise sometimes when out walking, going to the football etc. I would estimate total usage at not more than about 40 to 60 hours per annum - or about one hour per week on average. That is not very much and I am disappointed that they have not lasted longer.