I recently purchased the Patagonia Nano Puff Jacket. Patagonia products are in the top tier of outdoor equipment. I've owned the Down Sweater for just over a year now and it's been a great piece. The nano puff purchase was based on the idea that I should have a synthetic jacket to supplement the down sweater.
There must be some manual online that describes how to build a solid kit of equipment. I just thought it made sense to have a great synthetic jacket and a great down jacket. Maybe it doesn't make any sense.
The test: I've had the jacket for about a week now and the real test was today at Keystone Ski Resort. Conditions: Mostly Cloudy/Snowing, 20s, 30+ mph gusts, 7" of powder. Most of the day was spent in the backcountry area to the skiers left off of Cat Dancer on the North Peak. I wore the jacket as an outer layer, with a thermal Under Armour underneath.
The details: At 12.5 oz the Nano Puff is a little heavier than the Down Sweater. From my test run it didn't seem warmer than the Down Sweater, if anything it wasn't as warm. Although I was never cold in the jacket despite the chilly conditions. The ripstop outer layer of the jacket never let the wind break through the jacket. There were several occasions where I had to dig myself out of the powder, the jacket being completely covered in snow for more than a few minutes each time. The jacket never became soaked with water and never held any water. Throughout the runs I also had to put my forearms in front of my face to fend off the tree branches. I checked the jacket at the end of the day to see if the jacket was blemished in any way and I couldn't find anything. Another feature is it's ability to be compressed and folded into it's chest pocket. This is a nice touch for when you want to stow it on a pack and have it easily accessible for when the weather turns.
The fit: I own a medium Down Sweater and the size medium Nano fits somewhat differently. This is due to the fluffiness of the down and the Primaloft synthetic is more consistent and flat. I checked the arm length of both jackets and it appears to be the same, yet the Nano's sleeves tend to bunch up a bit around the wrists. Another thing is that the pockets on the Nano are really low and items held in them tend to sit below the waistline. This is my one gripe about the jacket. These pockets should be a little higher because the way they're situated in the current model is a little awkward.
The verdict: The Nano Puff is an exceptional jacket that is light and great at resisting wind and water. It also seems pretty durable thus far. It took a pretty good beating today. I would recommend this jacket to anyone that is looking for a strong all around jacket and layering piece when it's extra cold weather.