Very nice flat, warm clean and modern. We definitively liked the location. Would just be perfect with a good wireless hifi speaker ;-). Getting from and to the airport by train was fast, easy and cheap. Hauptbahnof is also a big mall open till 9pm. The flat is between 10min or 30min away of any famous Wien hotspots. We even found two good restaurants 200m away from the flat.
Arnd was there late to welcome us and helpful when needed.
I would definitively recommend the place at least in winter (impossible to use the patio with -10 deg. Outside)