Four years later we get this:
http://en.wikipedia.org/wiki/Historical_rankings_of_Presidents_of_the_United_StatesWarning -- this is a Wikipedia article, and it will not go unchanged. Events, better or worse between now and January 20, 2017, will shape the image of this President. It is not professional, but it seems neutral enough.
My take:
So far he is probably above average. He obviously can't compare to George Washington for defining the Presidency; any comparison to Lincoln or FDR requires a crisis as severe as World War II or the Civil War, neither of which is likely to happen. He will likely get much credit for adept stewardship of the economy because an economic meltdown that began to look like the start of the Great Depression ended in the equivalent of the spring of 1931 instead of the autumn of 1932. He has nation-changing legislation to his credit -- Obamacare -- like it or not. Sure it could be repealed, but it had better have a satisfactory replacement attached because he will veto anything that is not an improvement. Big reforms are always subject to subsequent reforms. He disposed of the most dangerous terrorist in American history.
Dubya, in contrast, is recognized as the worst President of at the least the twentieth century except for Warren G. Harding. Dubya gets the rap for two wars, one badly bungled and one that should have never happened but would not have happened except for his dishonesty -- and for a speculative boom that went awry with the potential of starting another Great Depression. Dubya may outrank Warren G. Harding because the Teapot Dome Scandal was the cornerstone of the short Harding Administration. Dubya had Enron, to which he had stronger and more personal ties.
Barack Obama has established what he is as President. One of his arch-rivals (Karl Rove) acknowledges that President Obama is
cautious. After Dubya, that is quite a necessary change. He is a stickler for protocol and precedent; he collaborates closely with intelligence agencies (contrast Jimmy Carter). He has run a squeaky-clean administration.