This jacket has it all over the others in the ventilation department. I really like the side zips that go all the way up as far as you want and down from the pit to wherever you want. That way you have the maximum breathability besides the goretex fabric itself. The sizing was fine with a medium to fit over 2-3 layers of clothing, and I often go with a small, but I wanted this to be versatile and fit over layers for winter as well as summer. Only drawback is the side zippers are stiff, so you have to firmly hold down the hem with 1 hand while pulling up hard with the other. Also, you need to practice adjusting the rear hood adjuster, barrel fastener before you are in windy conditions. It can be a little tricky.