It will be a mixed bag.
Naturally whether one personally likes him or not will have a major bearing. However I believe when history looks back on the "Great Recession" when he came into office compared to where he will leave it KPI or key performance indicators will show that GDP grew.
Unemployment went down, record foreclosures went down, and the stock market broke records, real estate values began to recover, and gas prices fell below $2 in some areas.
Osama bin Laden the planner of the events of 9/11 was killed, relations with Cuba were normalized (Note: We already were doing business with Communist China and Russia for many years.), Marriage Equality became legal for those who had been discriminated against, and the controversial ACA aka Obamacare was passed.
Much like when Social Security passed in the 1930s it has been ridiculed by many. Only time will tell if it becomes another "sacred cow" which most won't want to get rid of in 20 years like Social Security and Medicare is today.
My point is history books simply record (what took place) under a president's terms. All of the above actually have taken place.
However the adults of any given era are more prone to blame a president for anything that goes bad and not give them any credit for anything that goes good. There are always "underlying explanations" for both. How we (feel) about someone also has a bearing on how we view them. Political party (agenda) and stances also matters.
One thing is for certain if the next president is a Democrat it will mean the nation wants to continue to move in the same direction. For it is unlikely a Democrat will repeal Obamacare or undo any of Obama's executive orders.
The next election will be about party platform and ideology more than ever. Naturally if the person one votes for does not win they are going to be upset with just about everything the new president does.