I haven't worn this guy backpacking yet, but wearing it around it's clear it is a warm jacket. It is half the weight of a heavy fleece and seems to deliver twice the warmth a fleece would. Definitely an important piece of cold weather gear for the lightweight traveler. Waterproof down is a huge plus too! Just can't wait till they figure out a synthetic that does the same thing!
This review was written in the old system and had content requirements that are different than reviews written today.