For his incompetence.
For forcing the Taliban out of power in Afghanistan (a very good thing), but then letting them regain power by moving troops and money from Afghanistan to his ill-considered war in Iraq.
For squandering all the good will that American had been building up in the decade before he took office.
For putting his own economic interests and the intersts of his oil business associates before the interests of his country.
For violating international law and his oath of office.
For starting a war against a country that was not in a position to attack us while letting the monsters behind 9/11 go free.
For ignoring people's rights.
For putting his friends into office instead of looking for qualified candidates.
For letting the people of New Orleans suffer and die even though he had FOUR DAYS warning that Katrina was going to hit hard.
For taking the most vacation time off of any president in the history of the US.
Most of all, he'll be remembered for his blind arrogance that led the world to the brink of yet another world war.