Since a candidate cannot compare himself with people he doesn't know, all he can do is describe his incredible passion and desire and commitment and ... well, basically beg for the job. (Way too many interviewers ask the question and then sit back, arms folded, as if to say, "Go ahead. I'm listening. Try to convince me.")

And you learn nothing of substance.

Here's a better question: "What do you feel I need to know that we haven't discussed?" Or even "If you could get a do-over on one of my questions, how would you answer it now?"