I picked one of these up with points, and I have nothing but good things to say about it. Everything that you would expect from Arc'teryx. This thing is not fantastically thick but keeps you really very warm, due in part to how well and how closely it fits. I don't get too many days out here in CA that are cold enough to wear this under a thick jacket, but it is definitely my go-to piece when it is. This base layer is also quite usable as a sole layer when doing high output activities on chillier days as it keeps you warm but breathes and wicks extremely well thanks to the polypropylene content. These things are expensive, but definitely beat the heck out of your old pair of long-johns or thermals!
"Great base layer in the cold, fits snug"
I have worn this while cross country skiing and hiking on the snow. Kept my core nice and warm and the zip neck was helpful as I heated up and needed to cool. If ordered in your true size it is a compression fit. Body and arms are plenty long which is huge for me as i am 6'5" and have a difficult time finding clothes that fit well in these areas. Very comfortable if you like the compression fit. I ordered another a size up and am waiting to try that as well.
"Great next2skin base layer for Extreme temps"
I have bought into the Arc's Phaze technology - it is pretty incredible at moving moisture(sweat) away from the skin. As with almost all Arc stuff, you best be athletic - because its a fit fit. I am 5'9" 170lbs - in a good way - and the Phaze medium hugs.A note on the SV - by itself, its not that burly, but once you start an aerobic activity you realize that the SV is probably overkill for anything less than deep winter temps.....