At best, yet another two-faced politician who promised one thing and did the opposite.
At worst, a national disgrace who sacrificed the rights of the American people in pursuit of an impossible goal of 100% security.
I think long term he'll be remembered for his election winning process (using technology, data mining, etc), and for public healthcare. I think that the scandals that have popped up are typical of our time, and not necessarily like Obama as an individual was sitting there installing wiretaps himself or denying tax forms laughing maniacally. I think those will likely be written of more as government bullshit than to Obama.
A dishonest man who looked good and was able to say what people wanted to hear, promised a lot of promises that he did not keep, a war criminal with Nobel Peace Prize and sexy wife - that's how I will probably remember him.