It's tight. I got the xl I'm 6 foot 200 lbs althetic built and realized I'm claustrophobic in the bag. I'll get over it. It says 56 degrees and up but I've used it in colder conditions already and it's been fine. Keep a base layer on. Big motivator for this was the packdown size. It packs down smaller then the nemo air pillow I have. Very happy about my purchase you will be too. Only thing I would warn is it's tight in the shoulder/chest area. My suit coat is a 44 and waist is a 32 if that helps in any way.
This review was written in the old system and had content requirements that are different than reviews written today.