Just received the jacket today, First impressions: Amazing quality, zippers are all smooth, fabric construction feels superb. Excited to see how this holds up for Canadian winter + skiing. Plan to use this shell as a rain jacket in the fall, and layered with fleece/hoodies/or even my North Face puffer in the winter for skiing.
I got a SMALL, I am 5'6, ~128lbs, and I typically wear a small in tops/shirts, and a small or medium in bottoms. The room on this is generous even in a size small, a medium would have drowned me. I would only suggest a medium (assuming the fit) if you are a person 5'9 - 6'0.
The jacket has an optional cinching at bottom, you can choose to leave it smooth and have it cover more of your bottom, I like having both options.