We stayed for one night in the appartement. It was very clean and we absolutely loved the location since it's near the city but also very quiet.
The appartement is easy to reach from the Westbahnhof and also the Hauptbahnhof even at night. It also doesn't feel unsafe walking from the tram station to the appartement since there are many lights around.
In addition, the check-in was very easy!
We'd love to stay again someday :)