Had one of these for the missus on the back (I know - why?). Binned it in the end. Sound idea, but actually a pain in the ass to use - always somthing not quite fitting right, earpeice not in right place, mic bit too windy etc etc. Phaff phaff phaff.
This was a few years ago now, so they may have sorted it a bit. Was v uncomfy under the hat back then too.