I live in Poland. We have both of them.

1. Soviet-era apartment buildings

PROs:

• everything within a walking distance (shops, schools, a clinic, etc)
• a lot of parks nearby
• fucking wind corridors
• you can't piss from your window to your neighbors coffe cup
• you will see some greenery from your window

CONs:

• tiny
• very low ceilings - you most likely won't be stretch your arm upwards.
• very bad acoustic - you can hear downstairs cutting green onions
• a lot of apartments on a floor (and very tiny lifts)

2. Modern buildings:

PROs:

• high ceilings
• you can piss from your window on your neighbor's bed if you're into it.

CONs:

• ... we have a whole wikipedia page about it: https://pl.wikipedia.org/wiki/Patodeweloperka
• I honestly don't want to talk about it, it's so sad. Generally speaking, bad quality (but deceptively good looking) places that cost too much, in a shitty neighborhood.
• no wind corridors so say hello to air pollution

Now, I know this sub tends to romanticize USSR, but during occupation (so until 1990) it wasn't that you had an apartment for yourself for every single person. If we just want to consider recent history (like 1980) then:

• your apartment wasn't yours - it was tied to your job. Like US healthcare. If you lost the job, you would lose the apartment. They were also limited to at most 1 per family.
• If you wanted to move to a different city to get a job there, then it could be impossible if the company didn't have free apartments there. Often it didn't. There was an semi-official apartment swapping market that often involved a chain of swaps in multiple cities.
• In practice you wouldn't get a bigger apartment if you had children. You could try to swap for it. Most apartments were overcrowded and multigenerational AND small. It was common for a 3 generational family to live in a 3 room apartment (not "bedroom", room).