We stayed at Oi Van's flat for 2 nights and it was great! Very easy communication by email and SMS, clear directions to the flat (we arrived in Wien Meidling and it was very easy to walk/metro between the station and flat!), and the flat was lovely.
Everything was very immaculate and new with everything you need for a comfortable, convenient trip (coffee maker, fridge, internet, great bathroom and shower, good water pressure!).
The location is halfway between Schoenbrunn and the city center, so it's really perfect for sightseeing, and easy access to grocery stores, ATMS, restaurants... The only tiny thing is that the street outside is a bit noisy with traffic, but it didn't keep us up at night.
We would DEFINITELY recommend the flat AND the host! Really great AirBNB experience!