I was looking for a nice warm winter vest for city life that would work over long sleeve shirts. We're talking temps in the low 40's, nothing too severe, and this vest fit the bill. It's very light, not too poofy and keeps your core nice and toasty. The outer shell does resist water on the occasional drizzle, I don't think it could handle a downpour though. Speaking of which, the shell probably would not fair well bushwhacking thorough the forest. It's thin and doesn't appear to be rip-stop, but it's not fragile either by any means.
Fit wise I'm very happy with it. As an example, I am 6'1" and 180lbs and went with a medium and it's perfect. I prefer a slimmer fit but not a tight fit if that helps. It would probably be too tight over a thick fleece, but in my use with a long sleeve thermal under a long sleeve t-shirt and this vest over it works great. The pit holes are snug, as they are elastic, and I found them to be no different than Patagonia's Sweater Vest which I also have and find the pits to be snug as well. I don't find them to be uncomfortable in the least bit.
All in all I'm very happy with this vest, I bought the Bright Navy and it almost leans towards the purple/violet hue side of color.