If you are looking for a huge apartment to sleep multiple people in the downtown area then this is a great choice. We chose it because our family (me, wife, daughter, mom, brother) needed a place where we could stay together but have separate rooms with privacy. That was certainly the case with this apartment. You can comfortably sleep 3-4 other people in this place.
We were met by Antonia and given keys and a brief tour. The only other communication we had was to get a fan replaced (there is no A/C) and that was handled promptly. No other communication was needed because everything was as promised.
If you are okay with a noisy, bustling downtown location then this place is fine. To get cool air in you must have the windows open and the fans on. The first night there was a loud event right outside. When shut, the windows are excellent and keeping the city sounds to a minimum but for comfort we kept them open at night.
The apartment has two toilets and two showers so that easily accommodated our group. We even used the kitchen to make dinner one night but the space and equipment is limited.
My mom has trouble with stairs but there is an elevator in the building. It is very small but made a huge difference for her getting around.
There are several good restaurants and coffee shops within meters of the building and very easy access to public transit. There is a lot of shopping nearby and you are close to many of the tourist destinations in Vienna.
I rated it 4 out of 5 stars only because 5 stars is the best of the best, however this was an enjoyable stay and I would recommend it.