Patagonia does their own thing with their soft shell material; mostly they mix in a little spandex to make those of us who came of age in the 1980s feel right at home. But there's nothing old-fashioned about the way the material moves: it's tough yet supple, and highly weather resistant yet breathable.
The rest is up to the design, and in the Alpine Guide pants the execution is top-notch. The Guide pants have evolved over the years into different versions, and if you don't need crampon guards or suspenders the 21oz Alpine will do you right. The back half of the waistband is elastic, the two-way zippered fly is harness friendly and there are a plethora of pockets: two deep hand warmers that double as vents, two welded thighs and single back, all zippered.
Patagonia puts more thought into their cuff design than some manufacturers do with the entire pant. The gussets lie perfectly flat inside until called into action by unzipping the 10 inch zipper and releasing the outer snap. Snap again to the inside and you're good to go around big winter boots. But wait, that's not all: you also get an elastic gripper strip around half the cuff and two tie-down loops. All this and smooth like buttah too. Nicely done.