We stayed here for our 20th anniversary with our daughters who both have additional needs. Christophe was a kind and generous host, making up the bedrooms we asked for and was extremely responsive, recommending to book our visits to the Eiffel Tower and Musee d'Orsay in advance and the local restaurants close to the flat.
It was a spacious, warm and comfortable flat, a short walk from the Metro and an easy trip on two Metro lines from Gare du Nord. Our daughters managed the spiral staircase fine and there was plenty of light and space to make them feel comfortable. I would highly recommend staying here.