I happen to live in a city that's primarily blocks (or as we call them: Plattenbauten) and honestly, they're pretty good houses. The structure is sound, after some renovations in the 90s and 00s, insulation and comfort are perfectly fine, and the surroundings are usually very green and pleasant.

The only real problem is, that these buildings are somewhat away from the city center due to superior socialist planning, so they are not super attractive for younger people.