As others have stated, the location is a key feature here. The apartment is walking distance from a bunch of stuff, yet the neighborhood is not full of tourists, which is great. You can really experience Vienna without being surrounded by tour buses and selfie sticks. And it's also convenient to the U-Bahn and streetcar, so getting around is very easy.
The space itself is nice and has everything you need. It's more spacious than I expected and very clean, perfect for relaxing in between activities. The portable Wi-Fi hotspot was particularly useful, something I now wish was at every Airbnb.
Hosts were wonderful - responsive and informative. Check-in was simple and straightforward. Check-out, even easier.
Overall it made for the ideal base for a few days exploring Vienna.