I think history is going to judge Obama similar to Lyndon Johnson.
Johnson had a great record with civil rights and social issues and left a fine legacy -- all of which is marred by the Vietnam war and his own stubbornness, or the way he was rolled by the generals and the CIA. That left an ugly stain.
I think Obama will be in the same boat in 25 or 30 years (supposing he has a second term). He'll have health care and, with luck, a few other achievements to be proud of, all tangled with the very disturbing precedents he's setting in the name of "security." They're invisible now but will not stay invisible forever, and will come back to bite.