Microblog Memes

Parenti, in Blackshirt in Reds, covers this topic excellently. He does not gloss over the flaws and corruptions in the USSR, but he is realistic in giving a fair assessment of their successes in the midst of their failures. A big point being what you mentioned above: the USSR had to continue focusing production towards just being on even footing with the US in terms of defense, to protect against the very real threat of the US overthrowing the government as they were doing in so many other communist countries. At no time during the USSR's existence were they ever not under attack by some outside force or another (the NAZIs, CIA, multi-national capitalist interests etc). Here's a good quote talking about the Stalin era and progressive policies during that time:

During the years of Stalin's reign, the Soviet nation made dramatic gains in literacy, industrial wages, health care, and women's rights. These accomplishments usually go unmentioned when the Stalinist era is discussed. To say that "socialism didn't work" is to ignore that it did. In Eastern Europe, Russia, China, Mongolia, North Korea, and Cuba, revolutionary communism created a life for the mass of people that was far better than the wretched existence they had endured under feudal lords, military bosses, foreign colonizers, and Western capitalists. The end result was a dramatic improvement in the living conditions for hundreds of millions of people on a scale never before or since witnessed in history.

Blackshirts and Reds: Rational Fascism and the Overthrow of Communism by Michael Parenti