The "great service" mentioned in other reviews was completely missing. Our interactions were cold and transactional: it will cost 35 euros more to leave our bags there before 4 because they get a lot of orders... etc. There's also a note taped on the door of the apartment written in an unpleasant tone as well, in both German and English.
The unit? It's adequate, with very very strong lighting. The bed is mediocre/thin. Many reviewers mention how "rough" the building is, and indeed, it is extremely rough, but not dangerous feeling, at least to us, although some others might find it so.
The BIGGEST PROBLEM, though, is the TERRIBLE INTERNET: we had to use our own cellular data for an important zoom call. The apartment is also loud, and there's no water boiler in the apartment, which has a completely generic IKEA furnished. there's a coffee maschine in the kitchen but no outlet on the wall. In short, we recommend not booking this unit -- there are many others in Vienna hosted by operators with more of a sense of humanity.