Among presidents in modern American history, he has also been a uniquely divisive force. It began with his forcing Obamacare through Congress -- the only major legislation in American history to be passed with no votes from the opposition party.
Though he has had a unique opportunity to do so, he has not only not helped heal racial tensions, he has exacerbated them. His intrusions into the Trayvon Martin affair ("If I had a son, he'd look like Trayvon") and into the confrontation between a white police officer and a black Harvard professor (the police "acted stupidly") were unwarranted, irresponsible, demagogic and, most of all, divisive.
He should have been reassuring black Americans that America is in fact the least racist country in the world -- something he should know as well anybody, having been raised only by whites and being the first black elected the leader of a white-majority nation. Instead, he echoed the inflammatory speech of professional race-baiters such as Al Sharpton and Jesse Jackson.
He has also divided the country by economic class, using classic Marxist language against "the rich" and "corporate profits."
Regarding America in the world, he has been, if possible, even more damaging. The United States is at its weakest, has fewer allies, and has less military and diplomatic influence than at any time since before World War I.
One wonders if there is a remaining ally nation that trusts him. And worse, no American enemy fears him. If you are a free movement (the democratic Iranian and Syrian oppositions) or a free country (Israel), you have little or no reason to believe that you have a steadfast ally in the United States.
Even non-democratic allies no longer trust America. Barack Obama has alienated our most important and longest standing Arab allies, Egypt and Saudi Arabia. Both the anti-Muslim Brotherhood and the anti-Iran Arab states have lost respect for him.
And his complete withdrawal of American troops from Iraq has left that country with weekly bloodbaths.
Virtually nothing Barack Obama has done has left America or the world better since he became president. Nearly everything he has touched has been made worse.
He did, however, promise before the 2008 election that "We are five days away from fundamentally transforming the United States of America." That is the one promise he has kept.