I do start out with another jacket (because of the sleeves) over this one when it is below 32f, but often remove it once get warmed up. Vapor barriers work by holding in the steam, so it is important to have more vents.

I live near seattle, the weather is not too cold here most of the time.

fishnet under wear works the same but it holds pockets of steam, and keeps the cold pant legs from touching your skin.

http://wiggys.com/moreinfo.cfm?Product_ID=35