This is by far the best cold weather sleeping bag I've ever used. Also the most comfortable. Noticeably better in every way than my old Teton Outfitter XXL.
Have only used once, but loved it. Granted it was only in 30 degree tempetures, but was very cozy and comfortable. I would highly recommend this sleeping bag.
This sleeping bag is pretty heavy and feels good in a cold tent. the liner is very comfortable to sleep in and the room is great for a good nights sleep in comfort. It is not something you would like to pack any distance. I am also worried slightly about the construction. Seems to be all single stitch construction. Time will tell.