My partner and I recently stayed at Celine's for one week. The best part of the apartment was its location-- in the heart of the Marais, with endless restaurants, cafes, grocery stores, shopping, and public transportation easily accessible. The space was fairly clean. Celine was also super friendly, helpful, and responsive!
But, the apartment itself was unfortunately much more worn than the photos convey and definitely not as bright, fresh, and new as expected (e.g., front door jammed, so it was hard to enter/leave, kitchen + appliances dated). It's on the ground floor, so, as others have noted, it's necessary to keep the blinds drawn so people can't see in from the courtyard, which limited natural light.
The biggest issue was the bathroom, which we found difficult to deal with for a week. The bathroom is small, not in great shape, and poorly designed, with a "walk in" shower that does not suit the space. Consequently, water flooded the bathroom each time we showered, which was a big pain. The shower head also leaked, which caused plaster on the ceiling to crack, the result of which was a space that just smelled a little dank and moldy. Additionally, hot water was a big issue, with the shower getting ice cold around 6-7 minutes in. This was frustrating and difficult since there were two of us.
All in all, the location makes this place, but for the price, the cons outweighed the pros, and I'm not sure we'd stay again.