It is an incredible system. It keeps Vienna affordable for average people.

The flats are really nice, just not huge. You also can't get one if you make a really good living. You also can't get one if you have just arrived. All fair enough, and it leaves a market for upscale flats and starter flats for capitalists like me.

Vienna has had a socialist local government since the end of WWII. This has resulted in a really "people-centric" city. Great quality of life.

Particularly because flats aren't so expensive, the average Viennese worker can still have a good life. This also makes for a relatively politically quiet city, because we don't have a huge percentage of people living on the financial edge and thus really stressed out.