FDR created the social blanket and led the country through WWII, Lincoln "freed the slaves" through a Civil War. I'm sorry but putting Obama (or any modern president) in that category isn't accurate.
You don't think that the U.S. in January 2009 wasn't in a dire situation? The economy was collapsing, we were in two military quagmires, there was a huge hole in NYC, American manufacturing was on the verge of disappearing, Americans were pessimistic about their future, and Osama Bin Ladin was still on the loose.
Fast forward to right now. The global markets are stable, the U.S. economy (and manufacturing) are coming back, the military quagmires we're in are ending, Americans are feeling optimistic about their future, and Bin Ladin is dead.
Not only that, but the U.S. health care system has been reformed, forming the basis for what eventually will be a UHC in the U.S.
Let's just say Obama wins a second term and nothing happens from then until 2016, Obama's legacy is still better than nearly every president since FDR. You just can't argue against that.
I think it's safe to say Clinton and Reagan are perhaps the best examples of good to great modern presidents, depending on your views. It makes more sense to compare Obama and any modern president to them, and when you do so he doesn't particularly stack up well (although you could argue Obama's legislative record is more impressive than both of theirs). If he manages to get re-elected things can certainly change; imagine how different Clinton's legacy would be if he was not re-elected for instance.
Clinton's legacy was stopped by Republicans. Obama did what Bill and Hillary couldn't do, and pass Health care reform. Clinton's legacy was further tarnished by the Lewinsky scandal. I can't consider a president who was impeached for perjury to be considered a great president. He was good, but his personal faults will forever tar his presidency.
Reagan is in somewhat the same boat as Clinton. He was a good president, but several things mar his presidency in really big ways, like the Iran-Contra scandal. He's enjoying a resurgence in popularity because the last Republican president was an outright disaster. However, that resurgence only exists because conservatives ignore just about every fact about his administration, and how he governed the country.
FDR and Lincoln were great leaders who changed the path of the country. I don't see how anyone could argue Obama is a good leader, or a leader at all to be perfectly honest; he seems more like a steward holding office until someone else assumes the presidency.
You honestly don't believe that we aren't on a different/better path than we were in January 2009?