I've rented quite a few apartments in Vienna, and this might be the best one. Check-in was very easy, and the apartment itself is incredibly comfortable with a very thought out design that accommodates for anything you may need. It was perfectly clean as well. Despite the building being located on a busy street, its very quiet in the apartment since the windows and balcony face the inside yard. I very much enjoyed staying at this place and would definitely visit again at convenience :)
The only thing I'd add is that for longer stays, a vacuum cleaner and basic set of cleaning tools is needed. Otherwise, great apartment!