I don't blame Bush for the Recession or the Housing Bust; for them, I blame Alan Greenspan and his disciples. (You can blame the presidents from Reagan through Clinton through George W. Bush who re-appointed Greenspan though)
I don't blame Bush for 9/11, but I blame him for a lackluster interest in fighting al Qaeda during his first eight months in office.
Bush certainly deserves blame for the Iraq War - 100%.
And he also deserves blame for putting America in a difficult fiscal spot because of his huge unpaid-for tax cuts. These made recovering from the Recession much more difficult.