Was it worth a shot?
Very complex issues.
Iraq was a sleeping bear, in his den.
Radical Islamacists come from all over.
I personally think we could have used our standing in the world after 9/11 to capture terrorists worldwide among our allies without invading Iraq, and stirring up a hornet's nest and spreading it's poison.
I think this war is spreading our resources thin, and drumming up heretofore unknown hatred and revenge towards America.
This could push the situation to a dangerous head.
After all, this "pre-emption" was an experiment.