The other reviews say it all, so I can only repeat:
Rainer is a kind, attentive and flexible host. I felt free to contact him whenever I had a question, but that was not really necessary during my stay as there were no problems.
Everything in the apartment that I used worked well. The check-in and check-out went smoothly. The flat is light and quiet, well-aired, and has everything that I needed and more. I brought a bike and could place it in the courtyard of the building. The location of the flat seems ideal to me, between the Prater, Donau, and the city center, and surrounded by grocery stores. I couldn’t have wished for more and am very grateful for the time that I spent here. Thank you again, Rainer!