sportsgirl236 wrote a review of Patagonia Nano Puff Insulated Jacket - Women's on August 12, 2014
Familiarity: I've put it through the wringer
This was an integral part of my gear for the Inca Trail trek where temperature changes were the norm, sometimes within the span of minutes. I got a medium since I was anticipating that I would be wearing layers underneath. It is looser I'd have been fine with wearing layers under a small. However, it didn't bother me much since I was very warm with the jacket, a half-zip baselayer and a t-shirt. There is an elastic-drawstring at the hem which I used to make the jacket look a bit more fitted.
For reference the evening temperature dropped down to 32F (wore the jacket plus 2 baselayers to sleep) and it got very windy and foggy at the top of Dead Women's Pass, a little under 14k ft elevation.
The jacket performed beautifully in the cold and wind but I wouldn't depend on this for wet weather. It's water resistant for misty weather but will probably get soaked pretty quickly with downpours. I wore it underneath a rain jacket and stayed warm and dry.