I used this on a trip to the Adirondack High Peaks area. It dropped into the 40s, but kept me nice and warm. I am a warm bodied though. It is LIGHT and packs really small. Who doesn't want a lighter and smaller pack?I am only 5'7" and 180 lbs. When I am wearing pants and a fleece jacket, it isn't uncomfortably snug, but there isn't a lot of extra room around me. If you're taller than 5'10" or so, you may want to get the long version.The material is pretty thin, so you'll have to pay a bit of attention not to throw it around. Watch out zipping the zipper up. The first time I zipped it up, I got the zipper caught on the material. No rips or anything, but something to be wary about.