Well, it was about 37F today. I ended up cracking the pit zips during a 4 mile run mostly made up of various climbs, and all I was wearing underneath it was a long sleeved cotton t-shirt. Other than that, it seemed to take care of the temp regulating for me, even at varying levels of exertion.

The chest and hand pockets are all zippered, and all three are lined with a very soft fleece. They specify that they are handwarmer pockets.They were also suprisingly easy to zip with gloves on. I stuck my cell phone in the chest pocket and my gloves in the hand pockets and they didn't feel bulky. It also has a drawcord hem, which I haven't had to use yet. I can also say that the velcro wrist straps comfortably seal out the cold against bare wrists or gloves.

As far as the temp ranges I have planned... I would imagine that it would keep me warm even on the coldest days, albeit with a fleece sweater and baselayer. I think my comfort breathing and my how my face and fingertips feel would be more of a deciding factor on bitterly cold days.