Great location, plenty of room for 2 people, well equipped with easy and flexible access (easy check-in process).
The apartment is only 5-6 minutes away from the Westbahnhof, so you can get anywhere in the city quite fast.
Privacy is somewhat obstructed with the glass bedroom door and the little opening hole in the bathroom door, so be aware of this if you're travelling with someone you don't know too well.
Other than that, the inside of the apartment wasn't hot even when it was 35C+ outside, thanks to it being on the ground floor and shielded from the sun by the other side of the building, which is a huge plus since many apartments in Vienna don't have AC and can get very hot in the summer.