Source: White House on Flickr.

As we head into the new year, one thing is for certain: much has changed with the Affordable Care Act over the past 12 months.

The program, which you probably know better as Obamacare, last year sustained countless software and server glitches that made it a nightmare for people trying to sign up for health insurance via the federal and state online marketplaces. This year, though, we've seen almost a complete 180 for the health reform program.

With that in mind, let's look at the seven most important facts you need to know as Obamacare's second insurance enrollment period hits its halfway point on Jan. 1.

No. 1: Healthcare.gov and state-run exchanges are functioning well
The biggest change between 2013 and 2014 is how well the federal and state health exchanges are running. With the exception of a few minor problems in my home state of Washington and a handful of other exchanges, consumers have enrolled for health insurance with ease.

Source: Covered California.

Last year's technical problems might have been a real turnoff for younger, more tech-savvy adults who are critical to the success of Obamacare. Young adults are often healthier and visit the doctor less often, meaning their premiums are highly valued by insurers. Young adults are also easily put off by technical inconveniences, such as a malfunctioning health exchange. A fully functioning exchange this year could eliminate any impetus to procrastinate in the enrollment process and might play a big role in getting young adults to buy health insurance.

No. 2: 6.4 million people have signed up via Healthcare.gov
Enrollment in the federally run health exchange covering 37 states, Healthcare.gov, is well above expectations in the early going -- nearly 6.4 million people have enrolled, many in the fourth and fifth week of open enrollment. In week five alone, when automatic reenrollments began kicking in, plan selections more than doubled from the prior four-week total, while applications submitted nearly doubled to 8 million.

No. 3: More than 1.1 million have enrolled via state exchanges
The state-run exchanges are doing their part as well. According to data collected by The Hill, 1,142,124 people had enrolled as of Dec. 17 in the 11 reporting states. Rhode Island and Idaho had not reported their enrollment figures at the time of The Hill's data aggregation, but neither state is expected to make a huge impact on the final enrollment total. Inclusive of Healthcare.gov's enrollment figure, Obamacare is an approximately 1.6 million enrollees away from meeting the Department of Health and Human Services' full-year enrollment estimate for 2015 of 9.1 million people.

Source: Covered California.

No. 4: The majority of enrollees were a part of Obamacare last year
The bulk of the enrollment surge in week five likely involved people being automatically re-upped in the plan they joined in the first enrollment period. Eighty-three percent of the 3.93 million plans selected in week five were re-enrollments on Healthcare.gov. Overall in this enrollment period, 70% of Healthcare.gov plan selections are re-enrollees. That isn't necessarily a bad thing as insurers need to retain as many members from the 2013-2014 enrollment period as possible, but having just 1.9 million new participants enroll in Obamacare puts the 6.4 million figure into a more humbling perspective.

No. 5: Many consumers didn't procrastinate
More consumers than I would have ever anticipated did not procrastinate this year when it came to enrolling for health insurance. I suspect this has to do with the fact that the exchanges are working properly in this session, giving consumers less reason to leave the site before finishing the application and plan selection process.

Also, a sharp increase in the penalty for violating the actionable component of the Affordable Care Act, known as the individual mandate, is probably luring consumers to to buy health insurance now rather than later. While the penalty for not having health insurance was the greater of $95 or 1% of modified adjusted gross income in 2014, it will jump to the greater of $325 or 2% of modified AGI in 2015.

No. 6: Affordability is still not a given
However, just because more people are insured does not mean consumers' real access to medical care has improved. A Gallup study released in late November, which accounted for the reduction in the uninsured rate in 2014, found that a third of Americans are now putting off medical treatments because of the costs (copays and deductibles) associated with those treatments. Two-thirds of the 33% were putting off treatments for what Gallup described as a "serious condition."


Source: Flickr user Francisco Osorio.

While adding more insurance options to state exchanges and Healthcare.gov has helped keep premium inflation under control, some Americans simply can't afford the out-of-pocket expenses that come with seeking medical care even with insurance.

No. 7: Federal subsidies remain clouded
Lastly, a cloud of uncertainty still overhangs the millions of people who receive a subsidy through Healthcare.gov. The U.S. Supreme Court is scheduled in June to rule in a case brought by various plaintiffs against the ACA regarding the legality of subsidies being offered to consumers via Healthcare.gov.

The language of the ACA allows "state exchanges" to offer subsidies. Since the federal government is operating the marketplace for 37 states, a ruling in favor of the plaintiffs could leave 5 million or more consumers without subsidies. Such a result could test Obamacare's survival.

Keep in mind we still have another six weeks of enrollments left, and we're likely going to see insurance membership patterns and percentages shift as we head into the home stretch. Thus far, enrollments have exceeded most expectations, but it's clear that hurdles to the health reform program remain.