How can Bush's War in Iraq be considered a major success?

I have 2 reasons to support that the war was at very best a marginal success & worst a horrible failure. 1)You can't change objectives mid-war & still have an overwhelming success. The main objectives for entering a war in Iraq was the capture of main leaders of Al-Quida(not sure of correct spelling) & Sadam was holding weapons of m destruction. So Bush got the clearance to proceed. We found several leaders of Al-Quida in Afghanistan but to my recollection no leaders in Iraq. And no WMD's at all. Then as it seemed overnight the objectives changed to liberation of Iraq people. WHICH IN ITSELF IS GOOD! But the reason we went was not accomplished. 2)To those that say the liberation is what made it a success or the amount of people liberated makes it successful, I ask you this. Is the liberation of a country from its current Government to a Democracy worth hundreds if not thousands of American lives? If so than one would be inclined to go into North Korea, Venezuela, Cuba, and Iraq's neighbor Iran. All of which 1 if not more of the following: Governments that aren't Democracies, Governments we have a very strong dislike for, or Governments that treat their people badly. But we all know invasions of any of these countries won't happen unless we get another perceived imminent threat like WMD's(which may or may not be correct again). So with that being said I'd like to hear some healthy dialogue, thank you.