Politically, Obamacare has had a terrible past few weeks. First there was inaccurate enrollment data (the administration wrongly included dental plans). Then there were Jon Gruber's comments on "the stupidity of American voters." And it was capped off with Sen. Chuck Schumer saying that passing the law was a mistake. That led to headlines like: "Dark days ahead for Obamacare," "The Obamacare controversy grows" and my own "Obamacare's terrible, horrible, no good very bad month."

But if you look beyond the political fights, the picture looks very different. Obamacare is, policy-wise, having a great month — maybe even the law's best month ever.

Jonathan Chait wrote a piece in New York magazine detailing four recent studies that show Obamacare is working. Some of it has to do with the part of the law that we all know the best — the coverage expansion to millions of Americans. Study after study shows that the Affordable Care Act has increased the number of Americans with health insurance. And this wasn't actually taken as a given at this point last year: there was some speculation that coverage rates might actually drop in 2014, as Obamacare's regulations cancelled millions of individual policies.

Then there are the parts of Obamacare that are about improving the health care system not just for the uninsured, but for everyone who goes to the doctor. And here, too, the law seems to be working.

Health care costs grew at their slowest rate ever in 2013 — in part due to Obamacare's spending cuts — according to a recent study in Health Affairs. And hospitals have been making fewer deadly medical errors since the Affordable Care Act began cutting Medicare reimbursements for institutions with lots of errors.

Chait's piece is worth reading in full, and I'd only add to it a few other tidbits of good Obamacare news that have come out in recent days. One has to do with enrollment: 2.5 million Healthcare.gov shoppers had selected health insurance plans by Dec. 12, in advance of a Dec. 15 deadline to buy coverage that would start in January 2015. This does not count anyone signing up in state-run marketplaces. Charles Gaba has kept track of those numbers and he estimates, when you add them all together, there are at least 4.5 million Obamacare enrollees.

And, one more caveat: that number does not include the many people who, when they signed up in 2013, checked a box last year to be automatically re-enrolled into their same plan for another year. The federal government will start those re-enrollments now, and it will likely mean a significant increase in the number of people getting Obamacare at the start of 2015.

To put that in perspective: at the start of 2014, there were 3.3 million Obamacare enrollees — and those numbers included both Healthcare.gov and the 14 state-based exchanges. This time around, and without counting any re-enrollments, sign-ups have easily surpassed that total in half the time.

Much of this likely boils down to the fact that the Obama administration (and states) built health shopping websites that actually work this time.

Enrollment is moving faster, and shoppers have more options when they turn up to buy. Health and Human Services put out a report earlier this month finding that the number of options on Healthcare.gov has increased 25 percent over the past year.

More insurers want to sell on the marketplace, and that seems to be restraining the growth of insurance premiums. The average benchmark insurance premium (the mid-level plan that the government uses to figure out how big subsidies will be) went up 2 percent between 2013 and 2014. In the years before the health insurance expansion, premiums in the individual market typically went up by at least 10 percent annually.

Obamacare, despite one political disaster after another, is delivering on some of the key things the law meant to change about the health care system. The health care system covers more people than it did a year ago. Costs are growing at a slower pace than ever before and hospitals are killing fewer patients. That's a lot of good news that's happened quickly. There's a lot of good happening with the law that, if you're just looking at the politics Obamacare, you'd never know was happening.