Does it work? Does it keep warm? I watched this video last month and the claims are pretty incredible
I have the sleeveless one from Darevie posted above, should be >2yrs by now... it's really good, the fabric is comfortable, and it's warm alright. I use even in some hotter rides because it helps keeping sweat away from the body, and avoids you being soaked.
also, even with that time and a lot of uses, it's still good, stretching/compression is still good too... very nice especially for the price
For rides down to like 5C I think it can handle well, below that I'd look for a 'closed' fabric which should be warmer