We stayed for two weeks in the apartment, and we were very happy with our stay. Everything in the apartment was in perfect working order, it was very clean, and very well suited for a longer stay also because of the facilities: a washing machine/dryer, dishwasher, enough kitchen equipment, etc. The bed is good. It is big enough for two persons.
The apartment is quiet (no outside noises) and cool (also because of the airco, much needed this time of year), and located in a classical building, which gives it a nice atmosphere. Such classical apartments inherently have smaller windows which limits the daylight a bit. Something that only struck me perhaps because I spent my time there working during the day.
The area in town is just perfect: wide streets, many restaurants nearby, a supermarket within short walking distance. Vienna is an interesting and lively place to visit. Restrictions because of the COVID-19 virus are sensible yet not too tight, and it is not so crowded which makes visiting Vienna at this time a very nice experience. People are friendly and polite.
We never met Renate in Vienna, but we can say she is a wonderful host. She responds quickly to questions and provides adequate and accurate information.