I just got one, too. My Medium, with the tags, weighs 7.8 ounces. The fabric is pretty interesting. It's 2.3 oz/yd2 nylon/spandex single weave soft shell. That's super thin fabric for a soft shell. Stretchy, but not super stretchy. It packs small enough into its pocket to be a suitable staple in the backpack.
Definitely much more air permeable than a 2013 Houdini or a Marmot Trail Wind, although not as air permeable as a Marmot Stretch Light (4.0 oz/yd2 polyester/spandex single weave soft shell) and not even close to the Marmot incline hoody.
I think it will be a useful winter top layer, a good compromise between moderate weather resistance and some breathability. It's like an "ultra-light" softshell hoody, although probably not as air permeable as the 15 ounce unlined softshells. However, the lighter weight and small pack size make it a better option to stuff into the backpack than those bulkier softshells.
it would have been a good piece the other day when I was snowshoeing after a big snow fall and melting snow from the trees was dripping on me all day. 35 degrees. The Alpine Start over a light long sleeve t-shirt or a Capilene 2 would have probably been workable.
For the price, I would like to see a bit more "design" quality. The materials are top rate, but the cut is pretty simplistic — all straight lines, no curved seams. Well below what you would see from Patagonia or Marmot. And, the obnoxiously large white logo borders on being criminal. Should have just left that off entirely or downsized it by 50%.
Likewise, the hood adjustments are function, but short of what I have come to expect from Marmot hoods, event those that are helmet-compatible.