Just bought this jacket, and the arms are long enough, but too tight to wear more than a long sleeved shirt underneath, and I have an athletic build. Would be fine with just a t-shirt, assuming you have slender arms. I am 6'3" and 160lbs, ordered the XL size, and still the forearms are too tight for my regular fleece jacket underneath. This limits my ability to use the jacket in the winter, as by itself it is not very warm. Good overall shoulder mobility. Chest is slightly large for my frame, which was expected due to my slight build. Construction quality is good, as is the fabric. Biggest complaint is the poor design on the arms, and the overly skinny cuffs, even for someone with pencil wrists.