The Darth Mauls are always pretty cool, but man, I can't even imagine putting on all that makeup. We've got a Darth Maul in my local 501st base and every time I see it I can't help but think "it's an awesome costume, but what a pain in the butt!"
It'd be fun to do a Darth Maul costume, sure, but I don't think I'd ever do it... I would never have the patience for the makeup. XD