I finally got a chance to try this bag out in what the bag is designed for, winter camping. We were out south of Cody, Wyoming doing a ski trip and the temps were right around 0 to -10F with wind chill in late-January. We camped at 10,000' a little below treeline. With just my base layers on and the mummy hood up I was plenty cozy in my bag all night. I usually have the problem of "cold spots" (feet and back) but I couldn't find any with this bag. The foot section seems to be stuffed with extra fluff. Also, there was plenty of room to stuff all of my wet gear to dry out from the day - boot liners, ski socks, gloves, water bottle so it doesn't freeze, skins and my shell pants and jacket. The material stretches comfortably but doesn't leave any dead air space, which if you've ever winter camped is an unpleasant finding at 2am. Overall, it's a great bag that I would recommend to anyone who wants a pleasant night in a tent when the temps drop.
For the record, I have used this bag for Spring skiing as well when it's around 25 degrees over night in the Tetons and it's great for that as well. Just strip some layers because it might get a little warm.