TL;DR: I stayed here for ~3 weeks, had a terrific time, and would definitely stay again!
Communication: Whenever I needed to contact Magali, she was available and promptly responded (modulo timezone differences).
Location: The location is superb! It's above a great café, next to a market that runs 3x a week and also a metro, close to the Parc des Buttes Chaumont, which is one of my favorites in all of Paris, and is generally in a lively area with shops, restaurants, etc.
The space: It's a very nice apartment and was a pleasure to live in. Despite being a light sleeper and my room being on the street, the windows do a good job of keeping noise out, and the street itself is fairly quiet at night, so I was able to sleep well. I'd note that I worked from the apt, and the wifi was exceptional.
Housemates: All of the housemates I had were reasonable and respectful, and it was quite easy living with them (one at time) over the weeks.