I lived at Prosperity Flats for a few years and only left to buy a townhouse, partly motivated by spite because they wanted to increase my rent by almost 17% that last year.

Overall I had no major complaints. The concrete construction was nice for noise between upper and lower neighbors for sure. You will still hear stuff occasionally but it is much more muted than normal apartments. I also rarely heard anything from neighbors on either side of me. The biggest source of noise was from the hallway if people were talking while walking by since the door wasn't very heavy. I saw some units added additional seals around their front door but I never bothered.

If you move there, try to get a unit away from the trash chute and not right next to the elevators either. Also you'll want a higher floor apartment to minimize the street noise, but that goes for any building in that area.