I skied this pant 150+ days last year. Touring, mountaineering, traveling, even used them in a rainstorm (long story) and not a stitch is out of place. They've always kept me dry, even in the rainstorm, and I haven't had to waterproof them at all. It is a thin shell, so warmth can be an issue, but if you just get a medium weight long underwear pant, you'll be fine. I never overheat in these when I'm touring unless it's 40+ degrees during the spring time and then I just open up the vents and they're fine. The cut is incredibly flattering which is nice compared to a lot of the boxy gore tex pant other brands make.
I'm typically a 4/6 (or 28) and wear this in a medium.