Costume is always an asset. Normal costume you have a lot to say about - if you're wearing suits or ties, and what color you want, and how it's going to be cut, and stuff like that, and whether or not you're going to wear a hat, and blah, blah, blah. But, when you're wearing a special costume, and of course, costume is probably the second ingredient in character, script being first, I always find that the costume does a lot to cement your character, to put it firmly in mind.
Morgan Freeman