We traveled to Vienna during our trip to Bratislava by train (definitely recommend: it's only a 1-hour trainride to Vienna!). Because we arrived earlier than the official check-in time, Thomas arranged that we could be there at 1 pm.
We liked: the location, the cleanliness of the flat, the hospitality of the host.
We didn't like that it was very hot in the flat. The small fan didn't help much. We definitely recommend to stay in a cooler place during summer times.