To really understand America, you must not only live in it, but also live outside it. Note: I am from the USA, and "we" or "our" refers to us Americans.

I spent 3 years abroad, recently returning to the USA this summer, and I will try to outline some of what I learned, although it is somewhat difficult as this knowledge has become ingrained in me and obvious as to seem to require no explanation.

- English as lingua franca

The average person doesn't realize how dominant English is as the world's language, how that dominance is reflected by our leading industries, and how the prevalence of English helps exports our culture, values, and by extension, our products.
For example, the majority of the latest scientific research is written in English, regardless of the scientist's nationality.
Every programmer across the world learns a rudimentary English just by virtue of being a programmer, as most programming languages are in English and the majority of programming technical guides are in English.
When travelers of different nationalities meet in a 3rd country, they speak English. When businessmen of different countries do business together, they speak English. As native speakers we have a built-in advantage. But our potential weakness is failing to understand different nationalities. Especially as the other countries grow in power.
I've heard, from the English-speaking Chinese in China: "We understand your culture and speak your language. You, on the other hand, don't understand ours at all. We have the advantage."

- Dominance of American cultural media, internet, and education
Hollywood movies, American music artists and bands, tech companies, and higher education all hold significant leads over whatever competitors foreign countries can muster. Besides China, the rest of the world doesn't use their version of Facebook, and none of them have the engineers to keep up.
The majority of the top 100 Universities in the world are in the USA. And most of the world watches American music and movies. Its ironic: a commonly heard stereotype is that Americans have little to no culture, when American popular culture is by far the most dominant in the world and unmatched in its breadth, choice, depth, and quality.

- US Consumerism
This is a little more complex, but you still can see this if you look hard enough: the world economic system is built around US consumers. Take a look at prices for electronics in Asia, for example. In the very places where the electronics are made, the retail prices are all significantly higher than those in the US. Samsung and LG TVs cost more in Korea than they do in America. Computers cost more in China than they do in the USA. I frequently found myself waiting until I returned to US soil before I made any big ticket electronic or computer purchases, because the savings were ridiculous.

Once you look into the price disparity, you realize that other countries, mainly the exporting ones in Asia, manipulate their currencies, and build their economies on the back of US consumers. It's a potentially dangerous cycle because our consumerism habit is encouraged and built-in to the system via currencies and our addiction to credit, making it a hard habit to break.

- the effectiveness of USA institutions: legal system, courts, law enforcement, Congress, media, higher education
Good governance and higher civilization aren't created overnight, and are not easy to develop. If you look at any 3rd world country, you notice immediately that the country often borders on anarchy due to lack of effective political / governing structure. Either the President is a brutal dictator, or the police are corrupt, or military generals are the de facto leaders, or the legal system is weak and the laws unenforced, and the list goes on and on. Effective government does not arise from air. It is built on decades or centuries of experience and stability. To maintain its effectiveness is a constant struggle against the evils inherent in man: laziness, corruption, abuse of power, etc. and a fight that seems to be slipping away from us in recent years.

The strong laws, governance, loyal military, and highly educated and productive citizens of a country are what make countries like America, those in Western Europe, and increasingly, some in East Asia good places to live.

Interestingly, even though reddit seems to hate cops, in my experience cops in the USA are paragons of professionalism compared to those in developing countries. It's hard to imagine, but cops there just don't take the profession very seriously. The standards of law enforcement in developed countries are another level entirely. And you can apply this "higher level" concept to the other areas I outlined above: judges, courts, the military, businesses, politicians.

If we let our vigilance slack, then the strong civilizing forces, whose bond make a civilization great, will begin to weaken, and the country's excellence will begin to regress.

Sorry, I took a tangent there.

- differences in political systems and their effectiveness
This is hard for me to explain because I consider it as self-evident as 2+2=4, but I'll do my best.
It's clear to me, and many other people who have studied political systems across the world, that democracy isn't a one-model-fits-all-countries panacea. Democracies (if you could call them that) often fail where there is no historical precedent or experience for it, and the populace is unfamiliar with or uninterested in participating in the democratic process. Uneducated, unengaged citizens are a recipe for democracy failure. Other factors that ruin a democracy's effectiveness: corrupt leaders and lax enforcement. The leaders just rig the elections and the enforcement just lets it all slide.

Another issue is public policy. Looking at what other countries have tried and how it works in their countries is like drawing up a theoretical policy experiment and then seeing the results before your eyes. The policy's results won't ever match 1-1 with your native country if said policy was implemented due to differences in culture and environment, but just seeing how others have done things opens your mind to the possibilities and forces you to understand a different perspective. The same applies to cultural values or mores. Often I have found myself in Asia in wonder at some common practice or another that is superior, in almost every way, to what we have in America. (And I've found the opposite as well).

- crumbling US infrastructure vs. the World's
"Crumbling" is a bit of hyperbole, but still, the first thing you notice when traveling is how new and modern the rest of the world's airports are compared to those in the USA. New York, America's supposed mecca of culture and a truly international city, has airports whose decrepitness puts lesser cities to shame. Don't get me started on the subways.

I would say that the USA has one of the best governing infrastructures, but only average (and slipping fast) physical infrastructure. Oh, and US Broadband speeds rank is #12. I'm particularly emotional about that one.

Overall, the US is still one of the best countries to live in the world for a number of its strengths that are unmatched, and will not be surpassed for the next several decades, if ever. But signs are showing that the civilizing fabric which holds our country together is weakening: deadlocked political process, income and wealth disparity at historical levels, the Great Recession, and what some might lament as a decline in values and morals into a disgusting morass of consumerism, selfish individualism, and celebrity worship.

But it could be all part of the cycle, and the future is still bright. The highly educated citizenry, and especially the youth(courtesy of all those student loans!), are some of our greatest strengths.

Meanwhile, at the risk of sounding un-PC, the uneducated underclass is our biggest weakness, although I'm unsure whether historically it is larger in size relative to the population.

I'm not bearish on America... yet. There are too many good things going for it. The energy, dynamism, ambition, and intelligence are all in absurdly high concentrations in numerous US cities. The political system just needs a little tweaking.