I worked at Cycorp as a contractor for a few months. Lenat was, without a doubt, the smartest person I ever met in my life. There are levels of scary smart... his intelligence was downright frightening.
I'm sad to see so many call his work a failure. His work was anything but a failure. I think this perception comes down to the fact that the company worked on many things that aren't public, and he do much publicity and self-promotion.