Spent over a month at Dejan's place. Dejan and his wife Jelena are super nice people. Their English is very good, easy to communicate with, The flat is relatively close to downtown. Mariahilfer Strasse is just a 25 min walk or 10 min by bus.
The neighborhood is really quiet and very safe. Vienna is a safe city in general. Pros: proximity to downtown, quick access to trams (6,18), an Imbiss store (Turkish convenience store / bakery) at the corner of the street very helpful on weekends Decent internet, new kitchen appliances, washer in the bathroom.
Some cons: the flat was not intended for long-term stay or people with lots of luggage. No TV no elevator (3rd floor may be challenging if carrying heavy luggage), no closets just a rack with hangers and three shelves.
Overall I enjoyed my stay and would recommend it to weekend travellers or people who travel light.