Perfect apartment. Large, clean, well-equipped (incl. coffee machine, dishwasher, etc.). Very comfortable beds. Convenient location. Just a few minutes walk to the city hall (Rathaus) and then to the Volksgarten park and we are almost at the Hofburg. The whole old town is within walking distance (to St. Stephen's Cathedral is less than 2 km). A few minutes walk is a tram stop (including line 2 to Belvedere), metro stations. The apartment is located in a very quiet area in the city center, you can leave the windows open and not worry about the noise. There are 2 restaurants and a cafeteria in the neighborhood.
Very friendly and helpful Owners. Very good contact with them. They provide us very useful information about parking rules in Vienna, gave us a address of long parking lot, information about city transportations etc.
I strongly recommend this apartment!