We only stayed at Rainer's place for 2 nights but it was great and we would definitely like to stay there if we visit Vienna again. The house is spacious and very very clean. Rainer welcomed us and despite the fact that we arrived late at night, he showed us some places we could visit and how to go around the city. He even had a map organized with the main points of interest.
P.S. Best toilet we've ever used!