I wore the Sorel Caribous in Antarctica when I was working there for a year. These boots are warm to about -35F and colder than that you need a different boot. They are comfortable to walk in because I walked in them a lot in weather that would be considered very cold in the U.S. I liked them so much that I brought them home with me and they are still in excellent condition, so they are durable. The only drawback that I can see is that they are big so driving a car or truck is difficult when wearing them. Other than that I would rate them as an excellent cold-weather boot.