I'm shy, paranoid, whatever word you want to use. I hate fame. I've done everything I can to avoid it.
If you stood me in a costume next to a computer graphic of the same-looking character, I think there would be a difference. And many movie fans I've spoken to would rather see an actor in a costume than CG.
I think if you get asked to do this, then that's called doing your homework, and I try and do it.

