Had the same experience.
Crossed no-mans land from Germany in modern Deutsche Bundesbahn train and then transferred to a decidedly less nice car pulled by the steam locomotive. I remember the ka-bang as we clattered over their older rail beds. Big difference from the sleek German trains.
And of course who could forget the Czech soldiers who searched us going in, and confiscated my copy of Time magazine for that week. Also went through my clothing and asked how many pairs of Levi’s I had - people were smuggling them in for sale. Commutards didn’t like that.
We didn’t have minders but were clearly followed when we were downtown in Prague. One of the dopes stopped in front of a women’s lingerie store and stared in the windows as we were looking at a restaurant menu next door. We took to whistling for him to keep up with us.
And all the women were pretty. After being in Germany for two weeks prior I was shocked to discover that Czech women were WAY better looking: lots of Paulina Porizkova’s teetering around on their stilettos!
It shocked me. I couldn’t imagine these women tolerating the drab, shabby life being inflicted on them by the dumbthug Communists. Since it was 4 years after the invasion, there were Russian soldiers patrolling in the streets in pairs - not a lot, but visible.
I knew then that Communism couldn’t last. These were people NOT having fun - you can’t live like that forever, and certainly not in the very center of Europe.
In August, 1972, when I visited the Soviet Union as part of a German student group, we flew from the Schönefeld Airport, outside of Berlin. Since this was in East Germany, with which the US had no diplomatic relations, and not East Berlin, I had to go through much more paperwork than did my German colleagues, but I had an easier time getting through East German customs than they did when I returned.
For an international airport, Schönefeld was absolutely dead, with only a handful of East Bloc airliners to be seen.