The apartment is quite central, and offers both easy access on foot to most major sites as well as via subway (nearest stop is Stephansplatz, ~5 min away). The apartment is professionally managed by an agency, which allowed for easy, quick communication.
The apartment is modern, but the bathroom (particularly the shower) was very small and the hot water would run out within 10 minutes. We stayed during winter, so this was more bothersome to us than it may have been otherwise. Further, there are no keys for the building nor the apartment, only key pads for which you enter a given code. This was great insofar as it allowed self check-in upon arrival, but the key pad outside the apartment had two digits that we could barely get to work, which created problems for us when we tried to get in (we’d often have to fiddle with it for 5-10 minutes before getting it to work). However, when I alerted the management agency to this, they changed the code within one day.
All in all, it was a fine stay, just with some hiccups.