I posted this to a thread about light expedition parkas, but I'll add my first impressions here too. The short version: I like it.
Field experience is always good, but I can easily recommend a jacket thats primary function is warmth. This is definitely warm, with very high quality construction. The full box wall makes it feel like you are wearing a well tailored sleeping bag for your upper body. The baffles are well stuffed, and the hood nicely envelops your head, but also fits well with a helmet. I'm keeping the medium, which has a good belay fit on my 6'2 170 frame, but without much extra room to spare. The M covers most of my butt, and I'd say the fit is fairly long, especially compared to the deliberately short rab infinty I've used. Speaking of which, for an extra 9 oz, this jacket is in a different league of warmth and coverage. I think this provides a better margin of safety on the coldest days. My medium weighs 675 grams and the large weighed 728 grams in a L, so its a little over spec, but the warmth per weight is still very good even if it turns out none of that extra weight is down.
I think I understand the concept of the reversible jacket with pertex endurance on one side and quantum on the other. You can wear the endurance on the outside when its snowing for better protection, then reverse it later to dry it out with body heat if any moisture gets in. I was skeptical about how this would complicate the design, but its well executed. Its not that different from having two zippered inside pockets, except they just mirror the outside ones. Big enough to fit a 1L nalgene in both inside pockets. I like the two color option, as one is more muted for town, and one is a nice bright blue for mountain stuff. Only thing I don't like is the little arm pocket on one side, b/c its cold against your skin if you're wearing it with a t-shirt, and sleeve pockets are kinda dumb, right? Also, its a super lofty jacket throughout with box baffles in the chest and arms, but I think its stitch through where the arms meet the torso. Small nitpick which I think is pretty common to most box baffled jackets.
Anyway, just thought I'd post impressions, since its still on the clymb for a very good price, and its one of the warmest winter parkas I've found for the weight. Between %46-%49 down!