Summary: I own a pair of Bose acoustic headphones that costs $300 bucks and sound like $600. These sound like $20, a big difference - but they cost about $5 so that is pretty acceptable.
Better sound than most ear pieces, easier to wear over a long period of time. Worth the money as a quick throw in the computer bag set to listen to the laptop/mp3 without bothering the neighbor folk on a plane or train. I like the folding mechanism, as they allow for tight packing.