I've had the Creative Labs HN-505 for about a year now and am completely satisfied with them. I'm not an audiophile with tons of different headphones and gadgets, so when I rate these, I'm comparing them to your standard iPod/mp3 player earbuds. I just wanted a slight upgrade from earbuds. I also wanted a small pair of headphones; when these headphones collapse, I can fit them into my pocket. Simply excellent.
One of the "attractor factors" for me was the noise reduction capabilities of the headphone. You just put a battery in the headphone and then click the noise reduction "on". It's not the greatest thing I've seen, but it does produce some white noise which cancels some background noise. It also makes the sound coming from your mp3 player a lot louder, so watch out.
The sound in general is pretty good. It's far better than the annoying little things known as earbuds which come with every mp3 player. The bass especcially stands out as much better than earbuds. However, because these headphones don't really cover your whole ear, you don't get the same richness and quality of sound as a better of headphones priced higher.