We stayed at Olga's studio apartment for a month. Its location is superb, close to the famous Mariahilfer Strasse. Moreover, you can walk to the historic center in 15-20 minutes. Mostly, we went everywhere we wanted on foot. And there are many shops around (markets, bakeries, etc.), which is very convenient.
The apartment is pleasant, with a very comfy bed. You have everything in the kitchen. And the wifi was working smoothly.
But we had some problems with the chairs. They were not comfortable. We work from home but could only sit on the chairs for a short time. So we would have preferred a more comfortable chair.
The apartment had an electric heater, and it was neither cold nor warm. We stayed in November, and the weather was not very harsh, so we had no problem. But we are not sure if the heating would be sufficient in the harsh cold months in Vienna.
Overall, we had a pleasant stay and enjoyed our accommodation.