We stayed at Seb's place for 5 days in December. Overall, it's a great option for a couple or single traveler coming to Paris - it's clean, centrally located, and super quiet. It's an interesting apartment, located behind a building in a small alley with a private entrance. This makes for a quiet, secluded spot.
There are a LOT of stairs and I would encourage visitors to bring slippers in they're visiting the winter. The apartment stayed warm and cozy, but the floor could get quite cold. Also good to be aware that the bed is located in a loft with a low ceiling, so my partner and I definitely hit our heads a time or two. But you get used to it :) the bed was clean and comfortable.
We would definitely stay here again - thanks, Seb!