How Wrong Was Iraq?

To me, we seem stuck in the same argument with hardened positions.  Fallows regrets not being more stridently against the war and chastises hawks (liberals and conservatives) to be more humbled and grapple more with their poor decision-making.  But I think people are far from convinced Iraq was as big a nightmare decision as Vietnam and while the strongest argument that liberals were right, ie there were no WMDs, was more of a mistake due to bad intelligence than a deliberate folly.  Of course, it strikes me the cost of being wrong the other way were much higher than being wrong in the way we were wrong.  That is to say, had Saddam had weapons, and we didn't stop him, that the situation would be much worse than the present.