If you are expecting some personal interaction with your hosts for advice or assistance on your stay in Vienna, this is not the apartment for you. They were out of town for the week we were there and the only way to contact them was by text or email.
When we arrived, no one was at the apartment to meet us. I advised our host that we would arrive on the 12:15 train from Budapest and would probably take a taxi to the apartment and would be there as soon as we could get a taxi. Our host texted me back and said, quoted from my text, " either me or my mother will wait for you at the apartment to check you in." We arrived at the apartment by taxi at approximately 12:40-12:45 and no one was there. I got a text from our host asking us where we were and I said we were standing on the street in front of the apartment. She sent her mother to let us in about 20 minutes later.
The first day, the overhead light and the only other lamp in the living area went out and then the light over the dining table went out and we were left in the dark for the night. The electrical problem was fixed the following day. We asked for additional towels since only one set was supplied for the week and the hosts said that the maid would deliver them at a cost of 5 Euros a set.
On the plus side, this is the best location in Vienna if you want to be in the thick of all of the major attractions. The apartment was clean with a good newer kitchen and bathroom with washing machine, but I would call it "Spartan" with Ikea barebones furnishings and few accessories, no frills, no extras. Functional but not especially comfortable. And, there is scaffolding in the "quiet" courtyard where the building is being remodeled. Workers were there for 1 day. Luckily, the workers disappeared after 1 day and then it was quiet for the remainder of our stay.