We (a family of 4 - 2 adults and 2 kids of 5) stayed for 2 weeks in early July. We used and stayed a lot in the apartment since our main reason travelling there was not sightseeing.
Positives: First, location was perfect. Close to subway, shops, groceries, restaurants, a very nice and large garden (Parc Andre Citroen) and a 50m swimming pool (piscine keller)... Apartment is rather calm, all double glazed windows are facing the building internal courtyard. Good point: electrical blinds for all bedrooms' windows.
The apartment is very bright, nicely refurbished and has all the comfort a family could need. Furniture and equipment were simple but efficient. Kitchen was small but very functional. Same for the bathroom (just need to add towel hangers and it would be perfect...). We had a very pleasant stay.
Noise sensitive persons beware: i) the apartment is in a nice old Haussmanian building and therefore we do hear the wood flooring cracking when people are walking on the floor above us and ii) being so close to the subway has an inconvenience: we hear the subway. It is more an issue in the late evening and early morning.