He left office with a 20% approval rating. He hasn't done anything to improve that.
In chronological order (somewhat)
Inherited a budget surplus, lowered taxes and spent the surplus ending by doubling the national debt
Was aslleep at the switch and ignored warnings from terrorism experts and gave us 9/11
Quickly squandered the political capital he gained after the 9/11 attacks through partisan politicing
Brought us the greatest attack on Constitutional rights in history with his "Patriot" Act
Avoided oversight on banks so that he could brag about the increases in home ownership which didn't end well
Started to unnecessary, counter productive, expensive, unpaid for wars
Gave us Medicare Part D that increased the cost of medication for seniors and enriched the drug companies
Destroyed much of the good will around the world by bullying allies into supporting his military wet dreams
Left office with the economy in shambles... A recession that had been more than a year long, Stock market had lost 30% and was declining rapidly, Unemployment had doubled and was raising rapidly, we had the highest foreclosure rates and the highest bank failure rates since the Great Depression
but don't trust me. historians rate him in the bottom ten of all our presidents!
EDIT: For all you brain-dead conservatives. Bush did not inherit a recession. the first Bush recession began after he tppk office and after he cut taxes. How bad was Bush? A couple of answers include Afthanistan and Katrina as his "successes!"