I stayed in the flat with my husband and two kids (6 and 2). It is a fabulous flat but considerably more cluttered than on the photos. It is also worth knowing that the Vienna tourist fee is charged separately (which I have not experienced in other places).
However, the location is really second to none. As someone who knows Vienna really well , I honestly can't think of a better spot. For families with young kids it's also great that there are so many toys etc, my kids were delighted with the place.
For my family it was cool to have more of an authentic experience than other santized air bnbs.