The biggest complaint I have is the noise level; I know way too much about my neighbors -- like how much they spent at the bar last night, or how the divorce settlement is working out. Apaprtment living means putting up with a bit of noise, but there is little to no insulation in between these units.
So - if you're thinking about buying one of these apartments as a condo, prepare for the extra expense of trying to re-insulate the walls so you can live your life privately. The sales company will most likely underplay this need; get it anyway. Me, I'm leaving and buying a real house.