The press never seems to notice that a large proportion of the negative opinion about GWB was and is from the Conservative perspective. Bush did not do enough to halt the approach to the cliff. That same mass of opinion views Obama as the descent from the edge and a prospective second administration as the rocks at the bottom. If there are any historians around twenty years from now an objective assessment will put Obama in a bottom class of his own and Carter a step above. GWB will probably be put in with Truman as immensely unpopular (but reelected) during his own time but seen far more positively in retrospect.
He will be remembered as the last guy with a chance to turn this country around and failed.