Obama is the 21st Century Harry Truman.
Both under appreciated by their country folk for the daunting tasks they inherited as president. Both have a divided government controlled by a minority party hell-bent on doing absolutely nothing. Both weren't supposed to win reelection, but managed to rally enough support against a NE elitist who campaigned aloofly and ultimately couldn't get it done.
History was not supposed to be kind to Pres. Truman. He left office with one of the lowest approval rating of any sitting president - only 32% of the country approved of the job he was doing at the end of his term. Nixon and Bush were the two presidents who fared worse.
Yet, most historians agree that Pres. Truman was one of the most influential presidents in American history. Certainly his record will remain divisive - the atomic bombings of Japan, the bluster of the Cold War - but his impact on America is lasting - his openness for civil rights and the continuation of FDR's New Deal.
My point isn't to compare Obama's record to Truman's - as they're two different politicians in two different eras. However, his legacy endures despite his initial unpopularity. In that regard, I think Obama compares favorably to Truman and, under the lens of history, his presidency will endure as well. It might not go down as a top-ten presidency, as Truman is often remembered, but I'm confident in 20 years, Americans will not come close to ranking him as one of the worst presidents in American history.