We had an excellent stay. The place is enormous, and comfortably warm even in February. Christel met us when we arrived and was phenomenally friendly and knowledgeable. She helped us get oriented in the city and told us what had changed since our last visit years ago, and where to find the things we were interested in. We got a tour of the apartment and told about some of its history. Everything in the city is walkable, so we could easily get everywhere both in the neighbourhood and in other parts of the city. The apartment itself was surprisingly large, and had everything we needed for a few days' stay. Can highly recommend both the apartment and the hosts, and don't be afraid to ask them if you are interested in some particular aspect of the city/neighbourhood.
Note for people with mobility issues: the door to the street is narrow and needs a lot of force to open, and there's several steps on the way to the apartment. Wasn't a problem for us, but could be for someone less mobile.