Matthieu’s apartment is excellent.
I stayed with three friends (4 adults in total) for a long weekend and the apartment hd everything we needed. Matthieu was easy to reach, gave great tips (which were all carefully written down too!), and made us feel very comfortable throughout the stay. Very clean, lots of light and very quiet at night.
Belleville is a very interesting neighborhood (especially if you have already been to Paris and are willing to explore more non-touristic places/experiences). The metro is right outside the door and the location in Belleville itself is perfect.
I would definitely stay again and highly recommend it!