That's pretty direct, I like it. I try to ask "what is the worst thing about X right now?" where X is the project/product/thing being worked on.
Caginess and dodginess in this answer is a flag. Of course, different interviewers will be more or less forthcoming and straight with you, but if the entire slate of interviewers hem and haw around the question, I take it as a bad sign.
An organization where people are afraid to be frank and call a spade a spade is hiding a lot of systemic problems.
