We enjoyed our stay at Serena's place. Serena was very kind and communicative, and the location was absolutely perfect. It was really great to have four bathrooms – one for each bedroom.
Due to some features of the house and the location (hip, busy on weekend nights, close to city center), we believe that the apartment is better suited to a younger group rather than a big family or group of older adults.
For instance, we found that the beds were rather hard and they were each two smaller beds pushed together, without any insert in the middle. The showers were also pretty small, and some of our older group members had a difficult time entering and exiting as some required a step up. The apartment was very neat and clean, but it is an old building (like many in Europe) so the space smelled musty at times and the floors were a bit grimy.
One thing to note that was not clear from the listing: the 4th bedroom doubles as the living room mentioned in the description. If you plan to use all 4 rooms as bedrooms, note that you will not have a living room to congregate in. As a result, our group of 7 ended up spending group time in and around the kitchen table. The kitchen did include a stove and pantry of eating supplies, but it did not include an oven or freezer.
For families coming from the US, also note that "first floor" in Europe refers to what we would call the second floor in the US. We did not realize that there would be a flight of stairs leading to the apartment, which caused some trouble for older members of our group with mobility issues.
None of these things were issues on their own, but they are details we'd like to have known in advance.
In some, however, and to reiterate the beginning of this message – this apartment offers great value and accommodation, as well as perfect location, for a younger, active group.