I have owned these since Oct 2011. I love them. They started frying out after about a year of use (used 100% in the gym weight lifting and cardio, so they'd get abused with sweat). I emailed Kinovio and told them the problem. They sent me a new pair within a week, no questions asked. In terms of comfort, I typically don't noticed them and for bluetooth, I think they sound pretty good.
I highly recommend them.