Very warm. Runs on the small size for a medium. Collar is rather tight. With a few improvements it could be great. Did I mention it is very warm.
Used this bit of kit in the Lake district of UK. I only needed a jacket to stop the wind as the Base Pro kept my torso nice and cosy. The only problem I had was I am small around the chest. If there was an XS I would have ordered that one. Without the jacket the S rides up on me and I feel like the Michelin man. I think the SF troops should be issued this kit for cold climates.
I absolutely love this jacket!!! It is light weight and extremely warm and comfortable. There is no need to wear any layers underneath. It's the best jacket I've ever owned.