We had an extended weekend stay (Wednesday-Sunday) in Vienna - and booked this apartment because of the location and facilities. The communication with Stefan before our arrival was very sufficient, and it is possible to arrive at odd hours since you are not dependent on the host to get access to the building and the apartment. All in all Stefan was an excellent host, making sure that our arrival went without problems: the alarm set-up had been changed the same day! - and during our stay: the outdoor temperature suddenly dropped, but Stefan advised on how to put on the heat. But in late Autumn/Winter I guess the apartment is quite warm - at least we didn't use the electric heating.
The apartment is very much about location: near major museums, shopping streets, parks, Naschmarkt etc. The one room is well equipped, functionally furnished and surprisingly comfortable for two people - with a very nice bathroom (lots of hot water!) and an effective kitchen. There was only minor noise at daytime from nabours or the corridor, and with the windows shut you could easily ignore any street traffic (it is a very small street with only few cars in evening/night). The entryway is not the most charming I have seen, and even though there is an elevator, the staircase is very easy to use even with suitcases - it is only two floors up!
We really enjoyed our stay in Vienna, partly because of the apartment as our perfect base. We will definitely recommend it!