My boyfriend and I stayed for three nights and the flat has the perfect conditions and all the supplies for a getaway! The location is perfect, just 30 seconds away from the nearest Ubahn Station and close to Prater and Donauinsel. The building seems old from the outisde but the flat is in good conditions.
The only issue was that it was a little bit hard for us to sleep as the weather in Vienna was really hot (more than 30°!!) and the buildings aren't ready for that temperature. But we thank Birgit as there was a fan in the flat so it made it easier for us.
In general, we are pleasant with our stay.