I have put off getting a down jacket for years. I liked the warmth but they always seemed bulky and expensive. This christmas my parents bought me a patagonia nano puff jacket for christmas and I am now left wondering why I waited so long to get one of these. I choose a synthetic fill over a down jacket largely because it is so wet here in the Pacific NW, the synthetic fill should stay warm even after a soaking in the rain. The jacket is far warmer than its 354g (12.5oz) has any right to be. The frst time I wore it on my walk to work I was pleasantly surprised at the microclimate that seemed to have set up shop around my body. I have yet to really put this to the test but it seems pretty comfortable with just a t-shirt underneath down to near freezng temperatures.