Most girls agree they're comfy as hell, and yes, you do feel slightly nekked, but when it becomes like a "uniform" for girls in highschool, I think it's horrible.
I wear uniforms to school so whenever we have a "grub day", EVERY SINGLE GIRL wears leggings, lululemon/tna pants, or some other sort of spandex-black pants with a loose shirt or sweatshirt. I hate hate hate it. Not to be the hipster here, but I'd rather wear jeans or shorts and a plaid shirt than look like myself, and everyone around me, just got back from yoga class.
They're nice to wear under ski pants though.