I had the plantronics discovery 665 and while the incoming SQ was good and fit was great.. it has no noise canceling at all so outgoing quality was fairly poor.. the mics pick up every little sound around you.. I returned it when the JB2 came out:
I've had the JB2 since release and I like it but it did take quite a bit of fussing to get a perfect fit.
The first thing I did was bend the crap out of the ear loop until it started pressing the JB against my face then after that I took a look at the earbud.. even the largest size seemed to come loose pretty easily if I moved my head around, I solved this by putting one PK1 donut foam over it.. this was very comfy and worked well, most any earbud foam should have similar result. I had however already ordered some jabra large size mini-gels

and when they arrived worked out even better than my makeshift earbud, the JB2 sits even closer to my head and is basically immovable.. yay
incoming SQ is not great, wind noise canceling is worthless (I think this is impossible with a mic based headset), other noise canceling works fantastic, volume levels are kind of a pain.. the loudest is too loud, 2nd to loudest is too quiet.. range is as advertised ~30feet
In the end it's worth the effort for a sleek little bluetooth if the price doesnt bother you.