I'm not sure about GDR, but in Lithuania Soviet housing is piss-poor. Apartments are tiny and dark, planning is crappy, heat insulation is shitty (at least renovation can somewhat fix it).. And nobody did anything for decades - just kept building same standard apartments. And even if they were shitty, they weren't building nowhere near enough of them.

On top of that, a lot of people, even families with young kids, got "dorm" apartments with shared kitchens/bathrooms/etc.

So yes, housing quality between USSR and modern housing is quite big.