I think he arrogant, and blinded by loyalty to those who don't deserve it, e.g., Alberto Gonzalez.
I think he makes decisions regarding issues like stem cells, based on religious rhetoric, and am frankly shocked he hasn't mandated intelligent design as a part of the "No Child Left behind Act".
Lastly, I think his ego led him to start the GWOT under false pretenses, which will now take decades to pay off. It's pretty simple, you can't spend billions weekly, and cut taxes, and pretend the bill will never come.
It will. Bottom line, we're not safer, we simply have more people in more countries pissed-off at us, and Iraq is no more closer to being a democratic nation then Iran is.
We could have rebuilt every school in the US for what we spent thus far, and had a lot more to show for it. Sigh.