I've sent my mother and my niece to Vienna on a 4 days trip, so I needed a nice and safe place for them to stay at. I am extremely happy I found Robert and Margit's place because they were amazed by the apartment as much as they were amazed by Vienna itself. From what I've heard, the apartment is spacious, but cozy at the same time. It is very well situated and has excellent connectivity with the center. It has all you'll ever need and more as far as the kitchen goes. It even has Netflix, which made my niece very happy. But the greatest asset was the incredible hosts that were extremely nice and accommodating.
I am happy my family had such a lovely experience and I'm hoping I'll get to meet the owners in person one day. Until then, all I can do is give this my highest recommendation.