I suppose I haven't found much success in complex tasks—it requires so much babysitting, fixing, nitpicking, and modification, I've found it rarely saves much time at all. This is hardly that surprising giving the complexity inherent in describing a task is often explored iteratively, but there's hardly a reason to burn so much money doing so if it doesn't save time.

Perhaps some domains allow a much better tradeoff between complexity of description and execution; perhaps there's a way to get it to exercise better judgement (for lack of a better term) without input from the coder. I just haven't run into this myself.