not good
I didn't like it. I returned it on the basis that the sleeve zips both broke.
I used it mostly for skiing and cycling, but it wasn't what I wanted. It didn't seem to give much extra heat, but when I got hot, its capacity for heat buffering was easily exhausted and it was VERY hot.
I traded it in for the BMW Airvantage vest which I have found much better for skiing and cycling, and I think for biking.
To be honest, on a cold day I use my electric waistcoat and nothing else is necessary.
ps I'm very pro PCM technology otherwise: I have PCM gloves (BWM comfort), a comfortemp helmet liner (system 4 evo elite) and PCM underwear (rukka outlast). All of these are EXCELLENT. Especially the rukka outlast stuff.