My medium fits perfectly; I am 5'11", lean build, 155lbs. FWIW, a size large I.D. eVent rain jacket fits over the Flight jacket with minimal down compression, a key consideration in building up my insulation and rain layering strategy! :-)
It's not cut long; I have a short-to-medium torso for my height (learned this while being sized for bicycles) and it does rise above my hips when my arms are raised. But my arms are long and my shoulders are a bit broad, and it accomodates both just fine.
My girlfriend wore it over the weekend, and 5'6", it was a bit oversized for her but generally was totally wearable. I think I'm probably at the upper end of proper fit for a medium.