I love this jacket. This is my first technical softshell and it has served my purposes so well. It has instantly become my favorite piece of gear.
I bought a small and a medium. Kept the medium because it allowed me to layer my Rab Microlight Alpine jacket underneath without any restriction in the armpits.
I sweat like a pig when I get my heart rate up and have gone without a shell of any sort when I trail run the past few winters because I always feel too clammy when I wear them, even if just on the descents. Granted, these were hardshells, but very lightweight and "breathable" hardshells. Well, they didn't breath well enough. This jacket is different and has performed flawlessly. Every time I get back to the car, true to form, my synthetic baselayer (which I love because it's so breathable) will be soaked through with sweat on the back but the jacket will at most have one or two minor wet spots, and that's with a pack on forcing direct contact between the two layers. It moves moisture so well. And today I took it to one of the three alpine zones in Vermont in my pack and brought it out just before I got above tree line. It did a fantastic job blocking the wind, though they weren't more than 30 mph gusts. On the decent, I felt waaay too warm but didn't want to fiddle with layers and rather just opened up all the zips (the big chest pockets are vents too) and kept going. Got back to the car. Sweaty shirt, dry jacket. Never got cold for a second.