I just got these and have only worn them once, but I wanted to get a review up for sizing since it appears to be a big issue for most. Figured more sizing intel the better, so here are my stats.
Weight: 255 lbs
Pant Length: ~32-34
Based off most reviews saying they run large, I bought XLs (I'm usually a XXL in most brands). The XLs fit me perfectly. Length and waist is spot on for me.
Although I will exclusively use these for backcountry touring, snowshoeing, and other alpine endeavors, I tried them out this weekend at the resort just to get a feel and fit. They performed great and honestly never even noticed them (aside from the suspenders occasionally slipping off my shoulders as many reviewers have pointed out. Crossing them fixed it). The pants are awesome, and yes, they are just a shell. My legs never get cold though, so the most I ever wear are some wool leggings underneath (usually in sub 20F only). If you're not a grizzly bear like me, then you'll definitely want to wear some thermals underneath.
I'll update on backcountry performance once I get them out a few times. And will upgrade to 5 stars if they perform (at this point, I have no doubt they will).