I (an American teen) also ate there in April 1990, with partially overlapping observations. The food was higher quality than anything else I ate during a week in Moscow, but it struck me as pretty standard McDonald's fare. As for the line, it was very long, but moved in fast spurts. Customers were admitted in waves and it was the most efficient retail orchestration I'd ever seen. There was some magical blend of Soviet queuing efficiency and fast food efficiency going on that left a deep impression.