We stayed in Arnaud's apartment with our 11 year old daughter for 10 days and were very happy with apartment and our host.
He met us at the front and helped with luggage, explained all the rules and use of appliances. We felt immediately welcomed after a long flight with fresh croissants and juice.
About the apartment . It is on the fourth floor , no elevator with beautifully restored old fashioned spiraled staircase. We had no problems with it. Apartment was roomy enough for three of us, fully equipped kitchen if you want to cook a quick meal instead of going out to eat. Clean separate bathroom with shower, he also has washer/dryer, but we didn't need to use it. Windows facing the street, have metal shutters that gave privacy, kept the room cool and the noise level low.
About the area. It is in the middle of Marais, Metro station is 3 minutes walk, plenty of supermarkets within 5 minutes walk, bakery around the corner, open seemingly round the clock with fresh bagguettes .