Important things to remember about how Obama will be remembered in history:
- It takes a while before a historical consensus settles. Generally with a political leader, they are described negatively when they first leave office, and then there is a revisionism over time which puts them in a better light. Also sometimes decisions they took in office take a while before the true impacts are felt.
- The real arbiters of how history will remember him are the people who had no real passionate view either for or against him. In any debate about Obama you will get some people who will give you chapter and verse about him being Muslim, bringing Communism to the US through healthcare etc, they are just the type that hated Obama from the start, probably hate Democrats and will never give an unbiased view. There will also I am sure be some hard core believers who will big him up whatever.
My guess is the general view will be something like: a leader with charisma who gave a positive impression of the US in the world, inherited some very difficult circumstances given he took office right after the financial crisis, had a Congress that was determined to block him on everything but in the circumstances achieved some quite significant things. But the hope and yes we can stuff of his campaign was a level of optimism that wasn't followed up with radical reform (largely due to those circumstances) and so memories of Obama will always be tinged with a bit of a feeling of "he was ok...but not quite what we expected..."