The location is great. If you are coming in from the airport, you can take a regional train to Bahnhof Rennweg Wien and it is about a five minute walk. If you buy a Vienna travel pass for the day (approx. €5.80) then the train ticket you need runs from the airport to the border of the city and costs about €1.80. For a weekend trip w/o much luggage, I highly recommend that over the CAT train (€21 r/t) or a taxi (which costs more). Once you know where the Rennweg is, you can also use that to catch the 71 tram, and that will carry you down to Karlsplatz (your gateway to the old city center) but also directly to the museum district (and the best Christmas market in the city). Obviously, the same tram can bring you back home again to Rennweg.
The apartment is a little quirky in the set up but very comfortable. Bring slippers or thick socks. They have a varnished concrete floor that can be a little cold for bare feet.