My family and I stayed at Markus' apartment just recently during a short stop in Vienna. It is a wonderful place. The pictures really do not do it justice. It is much bigger and nicer than it looks in the photos. Everything is pristine, clean and well thought out in the apartment. We wanted to stay for longer, but had to leave.
Markus is a great host. Very responsive and helpful. He even offered to help us with a cab as we left for the airport. Quite a pleasant experience. We will stay here again during our next trip to Vienna.