Nice stay in Vienna, the flat is really easy to reach (via subway), and near the places you would wana see!
We were three, a couple and a friend, and the room - nothing more than a studio - was not "private", contrary to what was advertised : no real separation between the living room (and the convertible) and the bed. So not a 2-rooms flat, but a studio.
Everything was working, the bathroom was clean, and we enjoyed our trip nonetheless.
Thanks Martin!