Fantastic place to stay!!! The apartment is located in a fantastic area - Marais. We loved the location. Walk out the door and there are shops and cafes. The apartment is also close to two different metros. The apartment is secured by an outside gate and by locked doors once you enter the building. We felt very secure in this area. There are courtyards in front and back but the building does not like you or your kids hanging out in them so as to keep the area quiet. This was fine with us as there is more than enough to do in Paris.
The apartment is three levels has three King size beds, two baths and two toilets. The separation of the floors is great and provides personal space between the top level (which has 2 bedrooms) and the bottom level (which has 1 bedroom). The middle floor is the kitchen. The bottom floor also has an impressive theater with full french cable stations, english news stations and a blue ray DVD player. If you plan on watching movies down here be sure to bring blue ray DVDs as some we brought for our child (non blue ray) did not play.
If you are considering staying here do it...we like nice things and nice places and this place is nice. Make sure to go to the cafe right next door La Petit Place and have a cafe crem for me.