Well, it's rated at 5 degrees for comfort and zero for survival, but I got into it in my living room earlier (as you always do with a new bag) and within a minute it was unbearably hot. This suggests that it's actually a bit warmer than my other (cheaper) bag with that rating.
It's actually very long, which is a bonus for me and I like the tougher lining material at the foot end (I just checked the item description on the Snugpak website and it says the lining is for sleeping with your boots on). Description
HEREIt packs small too.
A nice bit of kit.
GC