I would rate the apartment a 6 out of 10. It is clean, but the toilet, bath and kitchen need an update. The wooden floors give you the impression that the apartment was flooded and it sqeeks at each step that you take. The towels and bedding are very clean, but the kitchen ware is old.
It is not like the pictures.
The hosts are very nice and easy to talk to, but I really (nicely) recommend them to renovate the apartment.
The place is indeed quiet and near the Naschmarkt and Mariahilferstrasse.