This vest is great for people who are active outdoors in the winter. I bought it to play ultimate frisbee in the rain / snow this winter --> I like my arms free if possible so this vest seemed like a good choice. It is GREAT vs the wind so it keeps your core toasty even on those days where the wind is whistling all around you. I happened to have it as a mid-layer when I went sking w/ my son. It turned out that he had forgotten his ski jacket, so he wore mine and I wore an old coat w/ a broken zipper (which was just flapping open) and the vest underneath. While I won't say I was exactly roasting chestnuts underneath, I was doing okay even though the outside temp was in the mid-twenties. I couldn't have made it through the evening w/o this vest.
A couple notes, the vest is not very stretchy so the fit is important. I normally wear a large shirt, but the medium vest fits snugly (maybe slightly tight when zipped). Its not exactly a fashion statement, but functionally is a fantastic and versatile piece to have in your closet.
If you play outdoors in the winter, you'll never regret buying this vest.