"Commie blocks" can be quite nice if renovated and repaired regularly. The big problem with them is when they're basically left to rot, with elevators that haven't been inspected in over 2 decades, corroded water pipes, and jury-rigged electricals.
Edit: Should also probably mention that tenement blocks were absolutely perfect for their explicit goal: building pretty decent housing cheaply and quickly for post WW2 countries flattened by war.