Bought this for fall/early winter and definitely do not regret it. It is warm enough to wear alone without another jacket and as one of the other reviews says it looks great as well. Just be careful to not let your lady friends take it. They will fall in love.
This is a great lightweight baselayer for active pursuits. This with only a tshirt underneath kept me warm while hiking in 40 degree weather. Great athletic fit with nice thumb holes and chest pocket. Is slim enough for easy layering with a vest or shell
Planned to wear this baselayer for winter golf under a down shirt and a Primaloft jacket. But it was so toasty that I took off the jacket within 15 minutes. When the temperature rose to 45º I took off the down shirt too, and just wore this baselayer. Not only was it warm enough to wear alone, it looked good too.