If you're on the fence about getting this (as I was), just get it, you won't be disappointed. It's not bulky like other fleece jackets and seems to be pretty warm. Sizewise, it's true to Patagonia's jacket sizing (if you've every tried the nano puff, etc.). I am 5'1 and about 105lbs and got the XS. Def not too tight- there's room for a thin layer underneath. The fit is flattering- it's nice to have a jacket that doesn't feel so unisex. I have yet to try it out in super cold temps, but I'm pretty confident it will do the trick. My problem on my last trek was having some many bulky layers. I think this will solve that.
This review was written in the old system and had content requirements that are different than reviews written today.