The location is outstanding and the "bones" of the flat are good, but it was not in ideal condition when we visited for a 1-month stay. The sofa was stained and we has to wash the cushion covers ourselves before we wanted to sit on it, a window was cracked, the dishwasher wasn't working, many of the shelves in the refrigerator were broken, and there was structural damage from a leak in the bathroom that was only partially repaired and meant that the light in the bathroom didn't work. We were only given one set of linens at check-in for a 1-month stay.
In response to our queries, the landlord had the windows fixed and had a technician confirm that the dishwasher was broken, but not actually replace it. He did not address the structural repairs or the light in the bathroom during our stay.
The location is great, close to the Naschmarkt and Central Vienna, the bed is comfortable, and we ultimately enjoyed our stay despite the issues, but the flat needs quite a bit of maintenance before it should advertise itself as a 5-star experience.