We had three wonderful days in Vienna. The apartment was nice, clean and really good located. The City Centre (Opera) is within walking distance (approx 15 min). The flat is light and quite.
Alice provided us with all the relevant information, we needed. Unfortunately we hadn't the time to meet. As there is a key safe in the building this wasn't a problem for the check-in. Due to this check-in can be quite flexible. The cashless luggage storage in the building is also quite nice, especially if you arrive early and leave late, like we did.
As the apartement is quite new there are some small things (like a shower curtain or some basic things in the kitchen, e.g. spices or coffee) still missing. But all in all it is a very good apartment for four people and a perfect location to have some nice days in Vienna.