The decision to invade Iraq makes him a terrible President. The rationale was that Saddam Hussein was connected to Usama bin Laden and that Iraq had weapons of mass destruction, neither of which were true. Most would agree that "starting a war for no good reason" makes one a terrible President. Economics and domestic policy can be debated, but his legacy on both is pretty low. He might not have been as bad as Reagan or Clinton, but he did continue a trend of awful administrations with severe economic mismanagement and major human rights violations.