Libya was good for us, because Gaddhafi was a loose cannon who flirted with nuclear weapons. Syria was a failure because ultimately Assad didn't go anywhere, but at least it distracted Hezbollah from the matter of Israel and in turn helped to erode their reputation among Muslims (before, Muslims everywhere could get behind them simply because they're so anti-Israel; but now they're in the thick of a blatantly sectarian conflict, defending a Shi'ite government against Sunni rebels). Both were bad in that they sparked refugee crises, which lessened Europe's security and sparked a new wave of right-wing populism on the continent.
To be fair, this was right after we withdrew from Iraq. Obama was extremely reluctant to get the US involved in another war so soon, so of course it made sense to use ostensibly pro-democracy insurgents to do the dirty work for us.
By the end of Obama's term, oil prices were at their lowest in a long time (thanks in part to the increasingly prominent oil industry in the US) and employment was at its highest since the Great Recession. Economic growth was slow but steady. He wasn't hardline on immigration (for obvious reasons), but apparently he did help stymie and contain the rate of illegal immigration.
And also to be fair, even if you disagree with Obama's policies he had a lot of class. He was a good role model, and he was very presidential in his conduct throughout his presidency. There's no evidence to suggest that he was corrupt.
On the downside, his statements on BLM and the shooting of Trayvon Martin served to empower hooligans and other malcontents, shown by the crime spike starting c. 2014 after a decade and a half of declining crime (even if the goal for which these statements were made, ending disproportionate and supposedly unjust police brutality towards blacks, was a noble one). This opened old wounds in regards to race and paved the way for Donald Trump. When he left office, America was more divided than it was when he took office.
Likewise, his foreign policy gave the impression to our geopolitical adversaries that America was a power in decline, and especially starting in 2014 countries like Russia and China began to do all they could to undermine the international order. It could very well be argued that the 2016 Russian interference in the US election, as miniscule as it ultimately was, might not have happened did Obama take a harder line against Putin.
The "crown jewel" of the Obama Administration was probably the PPACA. There is no clear consensus at this point on how well this extensive healthcare reform package worked out, or whether it'll even get the chance to do so (thanks to Trump). Another was the Paris Agreement, which probably wouldn't have accomplished much and in any case is irrelevant now that Trump withdrew from it.
I think it's fair to say that the Obama administration was a mixed bag. He did some stuff right and some stuff wrong.
