All I ever hear about is how terrible the Soviet Union was at pretty much everything, such as the rampant corruption, collective farming not working, and that sort of thing. My question is, in spite of these problems, how did it become a super power?
Inefficiency is a relative thing. It was inefficient relative to the United States and a handful of other first work countries, but relative to most of the world (countries like China or India or Mexico), it wasn't really inefficient or undeveloped (which is a better word in this case). It had a strong heavy industry, good infrastructure, and a relatively well educated labor force.
The Soviet Union was a BIG country. It was the largest country in the world by far by land area, and the third largest by population. It had an abundance of most key natural resources. It had a huge supply of manpower. Furthermore, the USSR effectively controlled many countries in Eastern Europe. And then it had a network of alliances and relationships that spanned almost the entire globe, from Cuba, to Vietnam, to the Middle East.
It had one of the most powerful militarys in the world, with a massive arsenal of nuclear weapons. The Soviet Union spent a large share of its resources on its military (to the detriment of its civilian needs). This made it a significant threat to Western Europe.