I got these on woot about 4 months ago, and I love them. I have yet to have any problems with them, and I use them at the gym about 4 days a week.
But that doesn't come without a few howevers. They aren't very loud. So if you're looking for some bass boomin' action, look elsewhere. If you're someone with long hair, they can get a little annoying, because they hover on the back of your neck, and they are covered in a silicone like material. And the first two weeks or so that I had them, they were very tight on my head, but they did break in, and now they're very comfortable.
The sound quality is good, but you have to find the right sized earbud for your ears. I've never had a problem with the earbuds falling off.
I haven't heard it for myself, but my friend says that it has very good voice quality for calls.
All in all, I wouldn't buy them again if they broke, but they are a very good starter blutooth headset. After using them, I'm probably not going to go back to wired one.