I typically buy Medium for most Patagonia jackets, but this one fit me tight, especially around my arms. I tried this on with a fleece and it was even tighter. I suppose a Large would've been a better choice overall, but that would make the sleeves too long. I wanted to like the jacket, but for $250 (sale price), I didn't love it.

I bough this for a friend and it fits him perfectly. He's a slimmer guy and we bought a M. He wears it every day in the winter

Great jacket, windproof, weather resistant, very warm, but sizing does fit a bit smaller than the average piece of patagonia outwear. If you plan to have anything on under this jacket other than a t shirt, I recommend sizing up. Sleeves are a little short and tight and arm holes up by the should are smaller than usual. Other than the sizing being weird and having to size up from my normal XL, I love the jacket already.