I bought these to replace the various bundled earphones that came with mobile phones, tablets etc, but needed something relatively compact for travelling. In terms of quality versus price, I don't think you'll find much to beat these headphones. I ha...Read mored originally intended to purchase a pair of Sennheiser for about £30-40 but was a bit put off by the fact that they come with 3m leads, which would be a right pain on an aircraft, so went for these on the basis that they are more compact and easy to lug around.
I'd say the sound quality is perfectly acceptable for most mobile devices, with good bass response except for the heaviest tracks, although that could be as much down to the limitations of mp3 as any restrictions in the reproduction from these headphones. As far as wearing them for long periods is concerned, I've had no issues with any discomfort, but they can get a bit warm if you're heading off to exotic climates.
They fold down flat and come with a handy little carry bag, which stops the lead getting tangled round all the rest of your luggage.