Why Landsburg is no Levitt
Here is my hypothesis: Freakonomics was light on theory, heavy on (quirky) facts, and that is why it appealed to so many people. Landsburg is lighter on facts, heavier on (quirky) theories. He revels in the sometimes surprising logic of economics, which is not nearly as compelling for laymen as it is for econ professors.
By the way, I have read the Landsburg book and recommend it. But, then again, I am an econ professor.