I purchased these pants for commuting to work in the Fall and Winter, when it's completely unacceptable to get wet while riding. Matched with the Torrentshell Jacket, it's a winning combination. They are rather breathable for rain pants, but keep in mind they are not going to perform like a $300 pair of expedition pants. I'm 5'6" and 150 lbs., and I went with a Small; the fit is perfect - slim enough to not feel like parachute pants, but loose enough as to not restrict movement.
just got these and first use was sitting on the cold metal stands at a Pop Warner football game in the pouring rain - but I was dry! Good fit, easy on over regular pants. can roll these down and make them nice and compact to keep in your bag for that unexpected downpour.