We are a family of 4 - (2 daughters 17 and 22). The apartment had enough space for all of us to live comfortably for the 5 nights. As has been stated in previous reviews, there are 2 things you need to know: Lots of stairs and busy area - with the associated noise. If you are aware of both of these and plan accordingly, there will be no problems. Plan your outings so you don't have to go up and down too many times a day. I would recommend earplugs if you are a light sleeper or like to sleep in. It was very warm while we were there and the street noise on Friday and Saturday was a lot - but worse was the mornings at 6:30 when there was some contractors moving their equipment. This is part of urban living so just be ready.
The apartment is in a great location. Restaurants are in all directions and from directly below to as as far as you are willing to walk. 2 Metro stations are very close with Chatelet- Les Halles being a main stop and transfer point. The RER B is accessible using your Metro Paris ticket as long as you stay withing zone 1. We used it to get to the Catacombes and to the Eiffel Tower - with a change over. Grocery stores are close - MonoPrix is in the Forum Des Halles and has everything you need. There is a FranPrix a bit further that had a different selection - including Gluten-free Beer.
We found everyone in the area to be kind and helpful - in all of the stores and restaurants, we were greeted and the employees would switch to English without any problem -or stay in French for my daughters and wife.
We had an amazing experience and enjoyed the apartment.