Great Jacket..Better than other hard shells because it has the powder skirt where others do not. The pockets a great and easy to get to with a backpack on. You can see in the picture but there are also pit zips under the arms along with the 4 pockets on the front.
I am 5'7" 170 lbs with a 35" waist. I got a medium and it fit great but there is no room for any other layers under at that size. Returned it for a large and it fits great with room for layering but not baggy.

I got this as a replacement for my older Mammatus which had a collar problem. It is a huge improvement over the previous model - Gore Tex Pro Stretch is fantastic. It is much thinner than last years model but feels just as durable - and is much more flexible. I have not had it on a hike trip yet, but have done some cold weather biking / off-road unicycling with it and can say that it is very breathable - and warm at the same time. I took a long Vespa ride last night in the 30's with a Marmot Ama Dablam jacket under this shell - I was very warm, I even ran into flurries on the return trip. The shell is extremely windproof and waterproof - the new wind blocking powder skirt is a nice addition as too.

Bought this jacket recently as a full-on winter waterproof. Living on the Atlantic coast of Ireland I need a jacket that will rebuff howling Atlantic gales, and the horizontal rain that accompanies them. From past experience, Gore-Tex Pro Shell gives that little bit extra when it counts.
Having used the jacket, it lives up to the hype. Lightweight, extremely comfortable due to the small amount of inherent stretch in the fabric; seems to have hit the blend of pockets just right (compared to the faff some other jackets serve up..) and you can open the big outer pockets single-handed with a gloved paw. The hood is superb and the deep stand-up collar really cosy for snuggling into away from stinger headwinds. The collar is lined with a comfy micro-thin fleece.
I'd also recommend this jacket highly for ski mountaineering/backcountry touring. The light weight (relative to performance), stretch fit, thinner internal 'draft' skirt and general cut make it outperform my FreeThinker jacket, which, although feature-rich (better for resort skiing), has a much stiffer feel and is heavier in the pack, where it spends most of its time during a tour anyway.
I intend matching the Mammatus with a Magnus softshell (taped seams) for what may be the ultimate outdoor combo!