Had a nice stay with Qing and Felix.
Check in and Response:
Check in with Qing's brother in law was smooth and fast. She replies to questions immediately.
Flat:
The flat is nice and warm during the cold winter (heating was very good). The flat weren't similar to the pictures advertised (layout was similar but wasn't as big as expected).
Location:
Burgasse-Stadthalle U-Bahn station is around 5-7 min away from the flat, making it convenient to visit the attractions in the city center e.g. Stephans Cathedral (note the city center is not walking distance and is around 10-15 min away by U-Bahn; switching lines is slightly annoying after awhile). There's also a supermarket in the shopping mall next to the U-Bahn Station.
Amenities:
Towels and slippers provided. Coffee machine and the washing machine was nice. There was no dryer but wasn't an issue due to the cold, dry weather.