We had a wonderful stay at Liz & Jules. It is very clean, spacious, well prepared, located in the city centre, and quick access to the airport. The apartment is just a few minutes walk from the subway (& tram) station "Schottenring". You can go to "Schonbrunn" easily by the subway U4 without change.
There are several nice restaurants around which are open until midnight. But it is very quiet and safe area.
Easy check-in & check-out. Quick responce. The communication was excellent. We highly recommend their apartment to other guests !