The apartment has a super location. It is right beside the metro station, which meant we easily could get directly to Norte Dame, Louvre etc, and via one transfer to Eiffel Tower. It is also very close to Gare du Nord, which was good for us who came by train. In 5 minutes by foot you are in the area around Sacre Couer, and walk 10 minutes to get to loads of cafes and restaurants around Rye des Martyrs. You also have a restaurant in the ground floor of the building that is OK for a meal or a drink without having to leave the building.
The apartment is not large, but very nicely furnished, and the sofa bed works perfectly so there is room for 4 people. Beware that it is close to a crossroads, so there will be some traffic, also at night.
David was a good host who communicated well.