Sercan's place is super convenient, really just at the edge of city center. Within 5mins walk, there are two U6 stations. Nonetheless, I prefer walking 30mins to center as along the way, there are many interesting shops to look around.
The place is spacious, warm and well equipped as described. Facilities may be bit old but functional. No mould or funny smell. Wifi is strong enough. Can't say it is spotless but for this price in Vienna? It is definitely a good deal for a group of 3 or more people. Recommended.