The apartment is very nicely designed and located near a couple of small restaurants and only a 10 min walk from Sacre Coeur. We enjoyed the neighborhood even though the area around the metro station seems a bit rougher. The train stations Gare du Nord and l'Est are super close which is perfect when you arrive by TGV or take the RER from the airport.
The apartment is as shown on the pictures. Its most unusual feature is the entrance. The door looks a bit industrial and when you open it you are directly in the apartment.
The bathroom is central in the apartment and not very private. As a family this works but I would not recommend it to people who are not comfortable around each other.
The only thing that bothered us was the smell. We thought it smelled a bit like cat piss and we told Marie so. She had not heard it from visitors before nor smelled it herself. So maybe it was just us but she wanted to look into it anyway. Other than that we enjoyed our stay.