I wound up staying with Martin's mother, not the couple who's apartment it was. That was fine as there were fewer people in the apartment. The only issue was that there were two other sets of guests in the apartment, for which I was unaware. This made the bathroom harder to use as more people shared it, and it was less of a private experience. The location, while very close to the train station, was not in the best part of town. It took about 20 minutes to walk to each part of town (city centre and Gruenlokka) that I wanted to explore. The hostess was nice and the bathroom and kitchen were great to use.