I'm very happy with this jacket but I must say that I would not pay full price for it. I got mine fro $315 + tax on Altrec, although the prices seems to have gone up within the last week (back to $450). As fit goes, I'm 6'3" 180 pounds about, a slim but tall guy, and I wear a medium. In order to better layer I may trade it in for a large, I'd like to wear my R4 underneath it but this makes the jacket feel a bit constrictive when worn. The jacket's not bulky at all and fits like a glove, it's just that this fit doesn't allow for layering in my case.
Overall I've found the jacket to be quite warm and very comfortable. The "Made in China" label is a bit strange to read on an Arc'teryx jacket and I feel should warrant a lower price, hence my suggestion not to buy at retail but rather to wait for a sale price. Regardless, the jacket has performed well thus far and is very comfortable, the copper color looks sharp on top of it all.