We had a great stay at Katharina's and Peter's appartment. We were a family of 3 and stayed for 4 nights. It is very spacious, clean, well organized and has everything you need.
It is very close to all public transport - 10 min you are in the center, 5 min to Shanbronn. 2 min walt to Maria Hilfer Strasse.
The hosts provided valuable and updated information as well as maps and brochures about Vienna.

We definitely recommend this appartment for stay in Vienna.