Our host and hostess were very kind to us, offering a city map and some traveling tips which were extremely helpful for those new to Vienna. They were always quick to respond to our needs and never hesitated to give us help and favors whenever possible.
As for the apartment, I'd like to say it is perfect and would recommend it to everyone.
The location of the apartment is great, within 5-minute walking distance to the West train station, metro stations and tram stops, quick connections to main attractions in and around Vienna.
The kitchen is really well-equipped, even including salt and sugar (which I believe is often not found in rented apartment kitchens). The apartment is stylishly furnished and comfortable, just as the pictures suggest (or even better).
My family and I really enjoyed our stay in Vienna. Many thanks to our kind hostess and host, Katharina & Peter Kügerl.