The Patagonia Nano Puff Hoody is to insulated jackets what The North Face Denali is to fleece: mega-classic, durable and stylish. It's been around forever and basically started the lightweight synthetic jacket category. It is simple, layers well, and packs into its own pocket; however, many of its newer competitors are a bit lighter and warmer. Whereas other jackets focus on either weather resistance or breathability for high energy use, this piece is more of a general workhorse. That said, the Nano Puff has been around for a long time and continues to be a favorite for many, especially for multi-pitch rock climbing.
For a lighter, warmer, less expensive, more weather resistant jacket, check out the Editors' Choice award-winning Rab Xenon X. This model has a lightweight Pertex shell that offers greater wind protection than the Nano Puff Hoody's quilted design.
The Patagonia Nano Puff Jacket has no hood and is a little lighter and less expensive. Without the hood, it's easier to layer under other hooded jackets. For example, it much easier to wear under a ski jacket. It also just looks better around town. Both models are classics although the hoodless version is probably the best selling insulated jacket of all time.