This vest is my go-to choice for outerwear when it's chilly out. It's light, durable, and the pockets ALWAYS warm my hands quickly thanks to the fleece/tricot liner. Other thoughtful touches are the tricot-lined collar, the interior pocket that is zippered, a front zipper that is designed to never snag the fabric (and indeed, it never does), and a stuff sack. In weather that dips into the 30s and 40s, I'm comfortable with this vest and a long sleeve shirt or two underneath.
As for sizing, I've found consistency to be a bit of an issue. I usually fit a small perfectly in Patagonia stuff, but the first small I got in this vest was a bit smaller than I would have liked. I later got a second one from the fall 2007 collection and it was slightly larger and fit perfectly.
At $145, it's steep like most other Patagonia products. There are probably comparable vests for $15-$45 dollars cheaper that will be serviceable. But one of the main things that made me get this vest is Patagonia's dedication to quality and durability. I'm confident this vest will hold up for years and years. I have more information about Patagonia products on my blog, http://patagoniacommunity.blogspot.com/