We (a married couple in our 40ies) stayed in Itay's flat for 4 nights, and we are very glad that we made this choice.
The location is really great. It is not the very center of the city, but it is very well connected to the center. The tram station is literally in one minute walking distance from the entrance to the house, and it takes 7 minutes to reach Schottentor at the border of the city center by tram (which runs there every 3-4 minutes in the middle of the day). The metro line U6 is also quite close to the flat and can be used for connection with the main shopping street Mariahilfer Straße, and with the important train stations Meidling and Westbahnhof. A supermarket (Spar) is also very close (just near the tram station), and the only "proper" supermarket in Vienna which is open on Sunday (Billa at Franz-Josefs-Bahnhof) is not far away (ca. 8 minutes of walk or one station by tram).
Special recommendations for tourists: Strudlhofstiege (google it) and Liechtenstein Garden Palace are also very close to the flat.
The flat is situated in the 3rd floor, and there is an elevator. We got a big room with a big bed. As far as I understand, the host normally lives there, and the room is rented when he is on holiday. There is one more room where another person lives. The common area includes an entrance room, a small kitchen corner, a toilet and a bathroom with the shower.
The heating works very well (and can be adjusted). The flat is very quiet (the windows do not face the main street but rather a small quiet street).
The communication with the host concerning booking, check-in/check-out arrangements, etc., was very fast, efficient and non-complicated.
To summarize, it was a perfect arrangement for us, and we warmly recommend it.