We had a great stay as 2 adults with 3 kids. Fair size apartment, very clean, and everything seemed new and functional. There’s one bedroom with double bed, and there are 2 fold-out couches in the living room, perfectly fine for kids, maybe even adults. It’s in the northern part of Marais, not overly touristy, so it gives you a little sense of a normal Parisian life. Whole Marais, Pompidou, Norte Dame, République, Canal St. Martin,... are within short walking distance. Haut Marais itself is a nice & trendy area.