As written before, Las Vegas is a great place to meet people dressed as various celebrities. I have seen costumes ranging from bad to great. The Darth Vader that Matt and I saw was somewhere in between, but good for several laughs.
He wasn't too imposing, standing about 5'9", but I suppose he can't help his height (although he might have chosen a different Star Wars character if he was concerned with accuracy). Even more startling was a pronounced beer-belly. This Darth Vader had a big gut. It was very unsettling at the time.
I am not attacking his weight problem. I don't have a 6 pack either. We just found it pretty funny seeing a Darth Vader who looked like he just came from the corner bar.
Light sabre or not, I am quite sure Matt would have manhandled this wanna-be. Maybe Darth should have had one of those slimmers you see on late night tv.
Darth Vader and Matt in Las Vegas, NV-March 2011.