We arrived almost at midnight, and check in was made with the security staff. Apartment is very close to main train station (1min walking). Very stylish and clean. Its a newly built building, i remember it being under construction since last time i visited Vienna.
The apartment is on the 1st floor. At night it can be extremely illuminated near the window due to close proximity of street lights, but the double blinds block almost all of it. For some reason, sometimes TV didnt pick up any signal (probably an issue with the service provider).
Overall a great apartment to stay in city center. I would stay here again on my next visit to Vienna.