Temp is in the upper 30's this week, and after 45 minutes, I was still warm. Didn't realize it, but the lower back and armpit areas were a little damp. I had a LS baselayer on underneath. Guess I need to work on unzipping it for air flow.
Sizing is pretty good. I am 6'1", 200lbs and picked up the XL. My arms tend to be a little longer, and wish it had another inch or two in the sleeves while riding. That's my only complaint, but it is typical with most long sleeve clothing for me.