My family recently spent a week in this lovely apartment. We have two children aged 9 and 11.
The apartment itself is wonderful and quite large with room for everyone to spread out. It is very comfortably furnished and has a lot of historic character. The best part of the apartment is enjoying the view out onto the beautiful Place Dauphine while the trees were blooming. There were often groups of locals out playing games in the park space (as well as tourists) but it was quite safe and quiet.
Our check in was fine and we were shown around the apartment which is quite well equipped and is full of interesting books. The kitchen was small but is perfectly suitable to prepare a meal for a family (so long as the whole family is not in the kitchen!) and there was the added bonus of a dishwasher and washing machine in the next room.
The beds were comfortable and the two kids had fun in the upper bunk.
Being on Ile-de-la-Cite, it is often busy with tourists but the apartment was very quiet and peaceful at any time of day. It is a short 5 minute walk to find a bakery and grocery store.
We had a wonderful time at this apartment and would definitely recommend it to others.