Obamacare
If the Republicans understood the principle of s starting somewhere first and then making changes we would not have had a 100% partisan vote for this legislation. Not having ANY Republican on board meant that they sabotaged its many parts that required their votes, for example, funding insurance loss when people who should have been in the market did not. Republicans needed to be part of fixing what is necessarily growing pains for this complex legislation, and not sabotage it like being under big pharma clutches and keeping prscription drugs high.
Economic growth
I believe that the Bush fiscal stimulus following the 2008 housing and financial crash was (i) not large enough, and (ii) most of it went o bail out banks and keep States afloat financially. Thus little went into infrastructure projects. Obama's plea to Congress for more went abegging especially after the TEA party triumph in the 2010 mid-terms. We saw their antics like government shutdown, the sequestration and generally holding up measures that would have helped a more robust economic growth.
Syria
In spite of his success in removing Assad's gas weaponry (Russia destroyed these) without firing a shot, Obama's mandate to shut down wars needed the help of Middle East partners which did not happen for several reasons. First, the Bush-enabled Malaki government wanted the Americans out and they purged the Sunni military and officials who found a partner in the Al Qaeda breakaway headed by Al Bagdadi, thus incubating ISIS. ISIS became a phenomenon overnight after the Malaki soldiers dropped their American weapons and transports and flee from the sunni areas. It's not that the Obama administration did not see this coming (in spite of the JV remarks), but who could prefer for an abandonment like the Malaki Shiite soldiers. Then when the Shiite militias took over the Sunni villages and towns the Malaki forces ceded ground there. It was only after Malaki resigned that the americans were bcak in a special ops role and the tide turned against ISIS. Mosul is the only big part of Iraq left and it's about to start.
Turkey only wanted to bomb American allies Kurds in the border area as the Turks see Kurds as their existential enemies. The Saudis pulled out of the American coalition against ISIS after Iran became their main concern and they focused on the Houthis in Yemen. Jordan's approach is baffling especially after one of its pilot was burnt alive in a cage by ISIS.
The Russians also became a factor that under international law the Americans could do nothing about. they had a defense treaty with Syria and the Americans obviously were not invited in. Prior to that a no-fly zone (pursued by Hillary) might have helped but that was politically not possible with Republican and Democrats opposition for America to coninute financing a war that Arab regional powers should be doing. As long as the russians and Assad pummel the anti-Assad rebels and America concentrate on getting Kurds to be like the Iraqi army oftoday, then ISIS should be forced from Raqaa by the spring of next year, if not sooner.
There are tremendous areas of Obama successes, notably in turning around opinion in the rest of the world about America during the Bush era. He's tackled energy, the environment and institutionalized injustice against Blacks. He's brought back jobs and wages are finally rising. His public opinion rating is soon to touch the 60% mark. He sure would have regrets like nay other outgoing President.