In The Rove Presidency by Josua Green of the Atlantic (Sorry, but to get the full story, you'll have to pick up a paper copy of the magazine), Green paints a picture of Karl Rove as a political adviser who had the run of the place. A major problem with the Younger Bush presidency was clearly Rove's desire to remake the Social Security program. For some reason, Rove didn't grasp the fact that it was turning even loyal Republicans off and there was no one senior to Rove other than Bush, Bush gave vastly too much authority to his political adviser (The problem with doing that goes back to the old phrase "To a man with a hammer. every problem looks like a nail") so no one overruled Rove and the Younger Bush presidency commenced a tailspin shortly after they had successfully kicked Senator John Kerry's butt in the 2004 election.
I especially noted Bush's problem with over-delegating the work of the presidency in the spring and summer of 2003. "Major combat operations" had been successfully concluded but it was clear that there was a substantial guerrilla force at large in Iraq. The testimony of Dr. Phebe Marr to the Senate in April 2004 (PDF) made it quite clear that there were two areas that Iraqis were concerned about and that failure to address these problems contributed to the strength of the insurgency "I would make clear we have no long term designs on [1. establishing long-term] Military bases [or 2.] Control over oil."
By the time Bush took his month-long summer vacation in Crawford, TX, it had become clear to bloggers like myself that Bush needed to sit down at the map table and hunker down with advisers and to really plan out how to deal with the growing insurgency. Obviously, he never did. This demonstrated a crucial disadvantage of what Joshua Green identifies as the "Reagan style" that Bush adopted, the idea that Bush would be the big-idea man and that his subordinates would fill in the details as they went.
As a Commander-in-Chief, the Younger Bush left and leaves a great deal to be desired.