I think history will treat him VERY kindly. He's been a visionary and a leader in the war against the Jihad. It's a life or death struggle until the end.
If anything he has not been aggressive enough.
Bush would have been a great President if he'd stuck to the war on terror. Sadly, with his attempts to remake the US to meet Daddy's globalist fantasies, he is condemning our children and our grandchildren to peonage and third world status; and with his de facto surrender to Mexico, he ensures the US will break up into ethnic diaspora.
In short, while he saved us from an enemy from without, as the enemy within he's betrayed us to the financial interests of Wall Street. (I guess that good "Christian" that he is, his Bible doesn't contain the verse about what profit does a man attain if he gains the whole world and loses his eternal soul.)