Was the Iraq war worth it?

This question is asked by Jeffrey Miron at the Libertarianism, from A to Z blog. His conclusion:

My forecast for Iraq's future: renewed violence between Sunni and Shiite as the U.S. funding that has temporarily bought peace dwindles. And any pretense of democracy will vanish. In the end we will have replaced one authoritarian state with another, at enormous cost.

Ending up were you began, at a huge cost, doesn't look like good economics.