Bought this bag early in 2012 after lots of research. First weekend I used it was Memorial Day weekend in the White Mountains, where temps hit 45 degrees one of the nights and I still had to vent just a bit. Used throughout the summer and early fall, and since I have the 66' version loved the 1lb 2oz weight and barely there size when in its stuff sack. Haven't actually been out where temps hit freezing, but I'm confident with a pad with a sufficient R-rating this bag would hold up nicely. So over all I think this is an outstanding quality, lightweight 3-season bag. Additionally, this was my first transaction with GearX and I was very happy with the transaction overall, thank guys!