I am almost 62 and weigh right at 150 pounds. I like the way the medium fits me (not a lot of loose material in body or arms). I use it when I have been out and find that I need a jacket. It fits neatly inside of my jerseys back pocket.
I've used a variety of lightweight full-fingered gloves this winter. They tend to be warm but not breatheable, breathable but not warm, or warm but inhibiting dexterity. These do it all. They keep my hands warm down to 35 degrees (I don't want to ride in colder weather) and it's easy to manipulate my Garmin watch or my bike computer without having to remove a glove. I REALLY like these gloves.