"So you're a fan of tyranny with a socialist face?"
Read some history. It was a popular revolution that brought russia and the republics out of the middle ages and into the twentieth century.
"Further, what's the evidence that the Soviet Union kept the US in check?"
I don't know about keeping the US in check, but boy it sure helped the working class and the intelligentia of this country that there was a Soviet Union around - no triumphalism then, oh no! Sputnik goes up, and lo and behold, there's money for science education and new math in the schools.
Joanna