technically they work as advertised. I am actually kind of impressed with the dual bluetooth pairing trick and the ability to syncronize the audio.
However, they're not small and light enough to stay in your ears during any form of activity. They're fine for sitting still leaned back in a recliner listening to music, but for that, so are full earphones with a wire. Maybe worn skiing, under a knit pull-over facemask?
Nice sound, interesting tech, useless headset.