Good things... Well, previous to his presidency, Bush Jr. had really flushed our nations economics down the crapper. During Obama's presidency, unemployment went from 10% to around 4.7%. He began talks to decrease tensions between the US and Cuba. Huge progress was made for LBGT rights, and generally made us look good on the world stage.
Bad things... Launched a healthcare plan that was an economic disaster, inflated the American deficit dramatically, really slacked on pushing LBGT marriage as a national issue, really slacked on doing anything about unwarranted police shootings of blacks, and was generally more talk than show.
Basically, he was mediocre. Had he of been a white man, he'd go down in history as entirely forgettable.