We stayed 4 nights. The apartment was very clean, there was hot water at all times and the heat was working perfectly. There was a coffee machine and capsules for 3 days for 2 guests. The metro line was a 2-minute walk. There were 2 big supermarkets 30m away. The key box is really helpful esp. when you have a late check in, like we had, past midnight. Also, at check-out, the hosts kept our bags in a room so it was very convenient. Everything was more than satisfactory. If I return to Vienna, I will definitely choose them!