Great location, near easy and frequent public transport and close to lots of restaurants. The apartment was very clean and the Natalie was a great host.
You are in the center of Paris, so don't expect it to be quiet. There is a popular bar downstairs, and a music festival when we happened to be staying. Free music on the street opposite, which we enjoyed from the balcony :-).
The windows are decently soundproofed so sleeping with them closed keeps most of the sound out. There are fans in the apartment.
Upstairs on the mezzanine the railings are not sufficient to be child safe, but that's the larger\better bed so you'll probably sleep the adults up there anyway.