These things are great! I am 5'9" and 150 lb., and the small is a perfect fit. Finding clothes that fit is not easy for me in this world of XL-through-4XL sizes--and a sometimes no small at all. These are stretchy enough to contour to your body, and look flattering even on my thinner athletic physique. I feel like a superhero while I'm wearing 'em! The fabric is fairly heavy, so they should be pretty warm on a cold night. But you'll probably need a jacket if it's really cold. These aren't that bulky.
I got the peacock blue and the green, I am just waiting for the khaki and maybe even the navy blue to come back in stock in the small size to get some more.