We stayed 2 weeks with our 4yo over New Year's eve.
Caroline is a fantastic host: reactive, resourceful and helpful.
The apartment is as advertised: great location, cosy and atypical.
It is in an older Parisian building in the most central location, walking distance to famous museums, parks, restaurants and historical neighbourhoods.
As for all older buildings, there are downsides. The insulation does not prevent outside noise or foot steps noise from the apartment upstairs. It is generally manageable but it could be a discomfort for most sensitive guests.
If you are having a family trip to Paris, and you are lucky with the weather, you will spend a wonderful time at Caroline's place.