I've got a Jawbone and I love it (one of the cheaper ones, picked it up on Amazon on sale for like $45), but I'm not one of those 24/7 bluetooth wearers. I pretty much only use it when I talk to 1) whoever I'm dating, or 2) my brother. Not many other people I can stand to talk to for more than five minutes
But, on the occasions when I do use it, the battery life is great, it's light, it stays in my ear, and they can hear me perfectly, even in light wind or when I'm sitting right in front of my fan. Sound quality on my end is a bit worse than using my handset, though.