Okay, when they decide to work
I bought these mainly for running but I do a lot of travelling around in my job so I wanted to replace my iPhone buds while I was at it.
When they work, the sound is fairly good but like with any other 'sports' earphone they bounce around and this noise resonates through to the ear. Luckily, due to the stabilisers, they (for the one time I could try then) seemed to stay in my ears so I could turn them up to compensate. This helped the bass response too. I can't vouch for extended sweaty use though because I haven't had a chance to test them on a long run.
When they don't work, they are useles. This seems to be alleviated by plugging them in, but this is no consolation when I grab them just before I run out the door for work and the charger is at home. I could take the charger with me everywhere I go but for the hassle it takes I may as well use my apple buds.