Darwin facilitated the check-in by meeting me at the apartment and showing me around quickly. There is a fully equipped kitchen you can use and separate toilet and shower to share with the hosts. The room is very large and has a cool décor. This apartment is an "Altbau" and not recently renovated, i.e. you get wonderful tall ceilings, windows and rooms but also some older appliances etc. The location is close to the Prater and the former/current Jewish neighborhood of Vienna. Very convenient connection to the main train station as well via u-Bahn. The room was a little chilly in the late fall but the blankets on the bed were more than warm enough for sleeping. There's also a desk in the bedroom and some tourism brochures, as well as wifi of course.
Darwin even let us have two friends over for a snack and drinks!