We spent several days in this flat and everything was great, we felt like at home.
Location is the best if you wish rest in a quiet district and go to visit many turistic places walking (15 min) or take underground (main line is 2 min walking).
Everything was clean, shower is perfect and is impossible feel cold here. Arrival and checkout are flexible and hospitality was the best.
If we come come back to Vienna, this flat will be our first choice! Thanks! :-)