Cardopskiwrote a review of Patagonia Nano Puff Hooded Insulated Jacket - Men's on May 18, 2016
Familiarity: I've used it several times
Fit: True to size
I have 5 Patagonia tops. 3 (2 pullovers and a zip up) of which are from the nano puff series (and even the pants for under my waders)--just to say I really depend on the quality when spending hours on the river. I have the down sweater, but prefer the nano puff for layering (mid layer) and its ability to insulate when wet (forget down doing that). The hood is a nice added benefit to the line as you're not always gonna have a beanie and a beanie doesn't cover up your mouth and nose. With this purchase, being the second or third generation of the nano puff series, I noticed the sizing has changed. A current MEDIUM used to be their SMALL, so order up if you are upgrading. I hope the elastic in the cuffs lasts as long as the first nano puff I have. They tend to get loose (rolling up sleeves under wading jacket) but they don't completely lose their elasticity.
I'd say it runs true to size, but I don't have the off the shelf kind of build. I have broad shoulders, chest and shorter arms for my height. I used to order the SMALL (I don't believe there was an XSMALL in the first generation), but now I order the MEDIUM. I put this jacket right up against the older SMALL and they are nearly exact in dimensions.