I am 5'10 185 lbs. 42 -chest; 33 -arms; 34 -waist; 16.5 -neck
I found some peoples reviews contradicting and confusing, therefor I had a difficult time choosing a size. My objective is to have a nice winter coat I can layer. The large feels big on me, but it doesn't look too bad. I can fit my monkey fleece coat or my 800 fill down coat underneath it and it doesn't look tight or awkward. I have a old summit series TNF that is Gore Pro in a medium and it looks better on me, but I can't layer under it because the zipper barely wants to close and it is way too tight. I know without ever having seen the Beta in a Medium it would look good and feel better, but I'm not sure I would be able to layer under it. The arms are long, but I have to come to terms with the fact that this is a technical outdoor sport shell and not the around town and hiking cross I wished it was, it is meant to go over winter gloves and all that, so I get it.
I drank the Arc'teryx Koolaid in buying this coat for how expensive it is (first Arc piece for me), and it is really nice. But I can be honest since I am not a cheese ball Gore Tech program guy or whatever and just a dude spending his hard earned cash. The coat is nice, but it is almost the exact same as my TNF. Same gore pro, almost same denier nylon on the outside, same taped seams, both made in China (great quality control, but maximizing profit). I like the main zipper on the Beta much better though. The TNF cost half the price, actually less since I bought it at a TNF outlet store new for $160. I took pics to back all this up, but the site won't let me load anything.
Bottom line: It's a great coat, but if you can score another brand with Gore Pro for much cheaper, consider giving it a shot.
It's a 5 star coat, but gave it 4 star for the price.
*In the pic, I have a MH Monkey fleece underneath