It was absolutely perfect! We loved the flat, it's spacious and well furnished. We could cook easily in the kitchen, the towels smelled very nice, we liked the interior design, the wi-fi works perfectly and it's close to the metro station, to the city center and to Mariahilferstrasse, a well-known shopping street! Moreover there's a supermarket down the corner which is very practical.
And Marina is easy-going and very helpful. She came to give us the keys and it was nice having a little chat with her.
In conclusion I highly recommend this place if you stay in Vienna!!!