As a liberal, I have mixed feelings on Obama.
I give him a C+
My criticisms: He's been ineffective in getting both sides of congress to play along. The ACA is a bandaid, when we need something like a single payer system. Like many politicians he flip flopped on gay rights until it became fashionable to support. The sloppy drone strikes have not made us any friends in the middle east, and likely made our standing in the area worse over there. We still haven't really invested in public infrastructure. Middle and lower class incomes have largely stagnated.
Positives: ACA is at least a step in the right direction, there's more young people and poor people with access to some sort of care at least, but still, see above. He's done a good job (eventually) putting pressure on society to support equal rights, and has been a visible supporter of better treatment of minorities and women. Being that I'd prefer us pull out of the ME at this point, I'm glad we haven't gone full boots on the ground in Libya and Syria. Unemployment numbers are going in the right direction.
I'm sure I could go into more on both sides, but I'd get torn a new one here, like usual