I have been using mine almost a year steady now, all year long, here in CA. I have had it down to 30 degrees but inside a bivi sac. I like the ability to use as a quilt for 2 people in summer. It also works great unzipped 3/4 as a top quilt for hammock camping. very versatile and well made.
Used it in San Juan Mountains in Colorado in mid 30 temperatures. Worked great, and was extremely lightweight!
It is well made, durable, super cozy and incredibly lightweight! I carved out 1.3lbs with this bag! This company is a home run for ultralight backpacking! And customer service is spot on perfection!!