This is a great light/packable rainjacket for hiking. It'll keep you pretty dry as long as it's not a total downpour (when it starts getting that moist stick-to-you feeling (which is to be expected with material so light). I'm 5'9" 170 36C and got the large. It fits nicely, but the hood is too short. If I put it up over my head, my forehead is exposed, even if I cinch it down.
I bought this more for around town fall weather because I loved the blue (it's gorgeous in person) and it's patagonia. I'm 5'9" 170 36C and I actually got the medium (usually do large) so it would be more fitted. It fits well and the sleeves are not too short. Very comfy, casual, flattering fleece. Probably a good fleece to have on treks (I'd probably use it for an extra layer in camp) but haven't used it for that.
This shirt is supersoft, very thin without being sheer, and nicely fitted. I've worn it as an extra layer in the mornings in the summer and love it. Haven't had it for winter hikes, but it has the potential to be a great baselayer. I'm 5'9", 170, 36C and the large is great. Bonus, the mineral color is lovely (not as neon as the picture makes it seem).