This is a nice little apartment. My family (my spouse & me, my mother, two children) fit well among the three bedrooms, and the dining table and couches could easily accommodate our group.
The kitchen is workable, but small. There's a gas stove (although even at their highest setting, the flames on some burners were quite low) and a decent set of pots and pans, reasonably sized to cook for a group of five (although it'd be tricky to make larger meals).
If you're staying during the winter, it's worth noting that the furnace is EXTREMELY LOUD, and that it can be quite uncomfortable to sleep with the bedroom doors closed -- the rooms will slowly get chillier and then become incredibly hot when the furnace (loudly!) kicks in. If you're not used to a lot of noise at night, you might consider traveling with a white noise machine or the like. And keeping a water bottle near your bed.
The hosts are quite responsive -- we didn't have any issues come up during our stay, but I get the feeling that they would have set to work quickly to address any.