The Affordable Care Act, or Obamacare, in essence, is a mandate for those without health insurance to purchase a plan. The government then contributes to lowering one's monthly premium costs. It's not a great system, but it's a better system. One that needs further improvement, such as greater subsidies or the creation of a "public option," that is, a government-run insurance policy that would compete with the private market. Yet, due to politically generated market instability and health insurance companies operating with little restraint, premiums and deductibles have gone up for many people, sometimes dramatically.
The ACA is a case of the federal government raising (slightly) taxes on higher incomes to provide subsidies and expanded health services. The Republican Party is therefore ideologically opposed—despite the fact that key components of the ACA were originally forged by the Heritage Foundation, a Republican think tank.
Nevertheless, the GOP was incensed by the passage of the ACA into law. They feared its success (which it can boast) and its popularity (likewise), and for that reason the Republicans have arduously sought to destroy it: "repeal and replace." The draft of the replacement healthcare bill recently presented by Senate Republicans—which predictably cuts taxes and services—achieved 17 percent popular approval.
So, for now, we merely have a bad healthcare system, unless the GOP can successfully make it worse. According to the 2016 Bloomberg index on healthcare efficiency, ranking 55 nations, the United States is near the bottom (number 50) nestled between Libya, Belarus, and Serbia above, and Jordan, Colombia, and Azerbaijan below.
Unlike its neighbors in that list, the US population has far easier influence in these matters.