For the price, these are a decent pair of headphones. I've had similar sennheisers etc before and the quality of sound, plus the sound isolation, of these JVC are certainly on par. The wiring is more durable than most - where frayed wires can cause disruption in sound and, often, loss of hearing completely in one ear piece.
Only reason this is a 4 and not a 5 star rating is that the earpieces themselves are larger than most others on the market and protrude from the ear a little more than I'd like. Takes a bit of getting used to but, all in all, for 1/2 or 1/3 the price of sennheisers, beggars can't be choosers.