My sister and I arrived in the evening and got a "flat tour" the keys, coffee and ice cream - so it already started perfectly. We had one room for our own (with a bed) and shared the toilet, the bathroom and the kitchen. If we needed something we could knock on the private room of our host.
We did sightseeing the whole three days of our Vienna visit and came back to the flat around 11pm everyday. That wasn't a problem at all for our host.
In the morning we woke up to a perfectly prepared breakfast - it was so delicious! We also had really nice conversations!
So, if you decide to stay in Vienna for a while I totally would recommend it!