The Nano Puff is one of the best jackets I've ever owned - love it. It's the perfect lightweight insulation piece and I wore mine a ton all winter long, practically lived in it - everywhere from chilly mornings in my basement office to traveling in Japan. It packs up super small into it's own pocket, so it's great to travel with, or to keep in the bc ski pack all the time as an emergency piece or to put on at the top of the hike.
The 60 grams of Primaloft is just enough to keep you warm, but it doesn't overheat once you start moving or if the temps warm up. The exterior shell does a good job of blocking wind and water, and is very comfortable as well. Can't say enough good things about this piece, and I'm looking forward to the cooler weather so I can start wearing it again

I really liked the sizing (moderately relaxed fit) and fabric weight, it functions perfectly as a wind-resistant sweater-type layer. If it had handwarmer pockets (and maybe a hood) it would be perfect. However, I am disappointed in the color choices. I tried the chartreuse first (hoping it wasn't as bright as in the picture), but just couldn't get past the acid green neon color. I returned it and ordered a black one, but I'm still deciding whether to keep or return it, in hopes of better color choices next season (grey? brown? maybe a more subtle blue or green?)

Was on an 8 day backpack in Yosemite first 2 weeks of September.
Jacket was everything they say, warm, compressible, lightweight, water resistent. Perfect fit.

Nano. Electric. Ty (up above) just about summed the function of the nano up, but I wanted to express how much I love this piece. It is THE quintessential do all, be all jacket. The electric green color seems to draw eyes from all sides, keeps me warm in the sierras at low light, I can't wait for it to snow and take it out!