Before writing this review I have to clarify that my stay was 3 months long and therefore far from being the normal usage of AirBnB. I lived there with my family (wife and daughter 2 years old) from October to December. I worked in a research institution in the 5th.
The apartment is very nice, cozy and "artistic". The host has numerous books, DVD and a beautiful collection of vinyl that you can listen while drinking a glass of Bordeaux looking le Sacre Coeur at night from the balcony. A nice old table with a candelabrum allows to make romantic candlelight dinners. At night there are not so many lights in the rooms (as usual in a parisian apartment). The kitchen is small but there is everything you may need for preparing your romantic dinners. There are insulated double glazing that keeps the ambient warm and silent. Bed and couch are super comfortable. The dimensions of the rooms are "Parisian", it means that are definitely ok for a short stay, but if you live there for months and you are used to spacious environment (like me) it can be hard to get used to it. Keep in mind that and apartment bigger than this in Paris it's impossible or super expensive.
The apartment is in a nice building with a lovely green courtyard with tables and chairs. Marcadet Poissonnier and Chateau Rouge stations are very close and you can take the line 4 that passes through the city center and connects to many famous places of Paris (in less than 20 minutes), one of the best metro lines. The neighborhood is very "colorful", with an high level of immigration, and it is very interesting to discover. But this does not make it the cleanest and quietest arrondissement of Paris. On the other hand the prices are very low. During our stay we tried French, Lebanese, Moroccan, Indian and Chinese cousine. We never felt unsafe there, but you have to merge with the neighborhood, do not act like an annoying tourist taking picture of everthing, especially in some folkloristic roads such as rue Poissonniere. You can easily go by walk to Sacre Coeur and get lost in the beautiful small roads around it. I liked also the near rue Ordener and the nice shops and restaurant around the Mairie du 18e, one of the most beautiful Town Hall of Paris.
Finally, Antoine is a very nice host, kind and helpful. He he will do whatever he can do to make your stay enjoyable.