It was a nice experience. The apartment is spacious, well appointed and well located, since you can visit most of the city's main attractions without the need of using the public transport.
Michael was friendly and gave me useful hints for my stay in Vienna. From what I could experience, I can say that the hosts give you a big hand to have a good time in the city: a remarkable benefit that they offer is the possibility to carry with you the wi-fi router, in order to use the apartment's internet connection even when you are around the city.
Very satisfied!