We liaised with Stephan in relation to the flat, he was lovely and accommodating on timings. The flat is large and spacious perfect for 4 people, Stephan provides a welcome bottle of wine on arrival which is a nice touch. We chose this location for the ease of accessing the heurigers around Vienna and also Danube island with its waterpark for kids.
The only drawback is the flat can get incredibly hot so you need to leave windows open on the chance of a slight breeze which brings occasional noise and cigarette smoke from outside. Others have already mentioned the building work occurring next door which starts at 7am weekdays.
I imagine this place would be great in winter with the fireplace.