I don't pretend to know how George W. Bush will ultimately be viewed, nor do I think the current assessments of him will be especially important in a few years. I would simply suggest that the popular notion that he was one of the worst, if not the worst presidents in history is simply silly. But as Hinderaker notes, the truth is that Bush never understood something that every successful politician knows: you have to service what you sell.
In the end, the greatest failures of the Bush administration were political. Bush was the first MBA President, and he always seemed to think that results would carry the day. He followed Lincoln, who wrote that if events bore him out, no one would remember his critics, while if events did not bear him out, a thousand angels swearing he was right wouldn't make any difference.
That's fine as far as it goes, but Lincoln went to considerable lengths, sometimes to the derogation of the war effort, to make sure that public opinion in the North stayed with him. And he was, in the event, saved by the victories won by Grant and Sherman.
Bush's great failing was that his focus was almost exclusively on policy, and he was unwilling to pay adequate attention to politics. This failing manifested itself repeatedly throughout his term in office. With hindsight, the beginning of the end for Bush was his unwillingness to defend himself when he was attacked for the "sixteen words" in his State of the Union address--words that were indisputably true. The same thing happened after Hurricane Katrina, the event that got his second term off on the wrong foot. In truth, the federal response to Katrina was both the largest and the fastest response to any natural disaster in world history. Yet Bush was never willing to stand up to his critics and make the case in his own defense.
That tendency to turn the other cheek was, in the end, fatal. Bush never cared much about politics. He was almost contemptuous of political leadership, willing to engage in politics on a sustained basis only in his two successful election campaigns. But he was a politician, and the job of a politician, as President, is to use political skills to lead the American people. Bush's unwillingness or inability to do what it would take to be an effective political leader, in the end undid his administration.
I can promise you this much: Barack Obama won't hesitate to use his political skills.