To answer your question, I worked for another year for that company and must have done about 100 interviews with that method. It wasn't perfect, but I found that it gave better results than the other stuff I had tried. Also, I found that the more I would bring the person in his comfort zone, the better appreciation I had for their qualities as a programmer. Also, that one question would always lead to a 30 minute discussion about their project (hobby or work). I would of course ask a bunch of other questions, but it was on the things they were the most comfortable with. I didn't have to ask them if they knew this or that, they would tell me all that they knew and we would discuss it. And wherever there was excitement, there was an indication of a good hire.