well the reasons given to the American public for going to war were
1) weapons of mass destruction
2) prevent terror
3) remove an evil dictator
4) secure oil interests
5) democratic Iraq would stabilize the middle east
etc..
1) no weapons of mass destruction
2) terrorist orgs weren't in Iraq in large numbers before we invaded now they're more of a problem
3) we captured saddam
4) Oil costs 4 dollars a gallon, though this would've happened either way
5) Democratic Iraq really destabilized Iraq and the whole middle east, Iraq has been more stable recently but the middle east is still on edge.
Really not much was gained form the Iraq war (unless you can through things and realize was that the plan was to control Iraq, Iran, and Afghanistan's oil pipeline as all countries border one another ps we haven't succeeded at this yet either)