Stefan was a really pleasant guy, and I enjoyed my stay with him very much. The apartment looks exactly as in the pictures, and everything that was listed was offered. The neighborhood is very pleasant and quiet. It's in the central area, within walking distance of Stephansplatz, the city center. The public transportation connections are good, and there are lot of neat shops and cafes nearby.
If I'm ever coming back to Vienna, I'm definitely staying with him again :))