Really comfortable, great mobility, really good fit, and they're as warm as they will get in terms of tight pants. Though my right leg has ripped all the way through the pant in the back of the boot area. They could be a bit more durable, but at the same time I don't take really good care of my snow pants usually.
They're the best pair of tigh pants made by a ski company IMO. I'd definitely buy another pair without a doubt.
As for the size, I wear size 30-32 for pants (medium), and went for Large, and they're the perfect size. With a pair of Armada suspenders, they're super comfortable.