I stayed there during my visit to Vienna with a friend of mine. Generally speaking, I'd recommend this apartment for everyone who wants to visit Vienna . A subway station was nearby (U4 and U6 lines), the apartment was clean and the beds were very comfortable.
However, there were no food plates (just two abused china bowls) and the heating system was compromised. Only after we talked to the host (Mary) we somehow managed to fix it and make it through the cold nights.
Thankfully, I think these problems can be easily solved, if not solved already, and the host was very courteous and helpful too, although I have to mention a small misunderstanding that took place: we were pretty sure we booked the room for 4 nights, not 4 days and due to that the host (kindly) told us to check out until the noon of the fourth day of our stay, not at the fifth as we expected. That's why I advise you to always contact this host before booking this apartment.