I loved Marie-Laure's apartment and would definitely consider staying here again on a future visit. The location is perfect – as a solo female traveller I felt very safe returning late at night, because there are a lot of restaurants nearby (one right across from the apartment, in fact) and the area is well-lit, with plenty of pedestrians passing by. It's also within easy walking distance of so many beautiful parts of Paris, so I hardly needed to use the metro during my stay.
Paris was experiencing a heatwave while I was there (41C on the hottest day!), and I was surprised at how cool the apartment stayed for most of the day even without air conditioning. The fan that Marie-Laure provided for me worked very well.
Check-in and check-out were both very easy.