Undo wrote a review of Patagonia Nano Puff Insulated Jacket - Men's on October 8, 2013
Familiarity: I've put it through the wringer
I rarely get too cold or too hot in the Nano Puff. It's very versatile for temperatures from about 15-50 F. With layers I've used it comfortably to zero. It sheds wind but breathes when it needs to and is water resistant. It stuffs to a very small size in its own pocket and weighs very little.
This is not my first Nano Puff jacket. It has been redesigned with a slimmer fit for 2013. If I weren't skinny, I would not like the new design. Medium fits me but I'm 6-0 with a 32 inch waist. If I was shorter or much heavier, the sleeves would be too long and the torso too narrow.
Heavy folks need not apply, unless they have long arms and go for the larger sizes.