Melusine was quick to respond and provided all the details I needed to make my plans.
The flat is lovely; extremely charming and very small. It was the perfect size for me. Everything - floors, countertops, shower, bedding - was spotless and well maintained. The views were gorgeous. The water in the shower was hot. The toilet is off of the main hallway which was different but not an issue. The bathroom was very clean, I don't think anyone else uses it regularly. It was a little more effort in the middle of the night but nothing too trying.
The stairs to the flat are quite a workout, especially with luggage. I was happy to have the added exercise to help with my croissant habit but access is definitely something to consider.
The location cannot be beat. I could easily take the metro but wound up walking to most things to see more of the city. There are many good restaurants, cafes and shopping in very close proximity as well. Best of all, I felt very safe walking around in the neighborhood late at night, by myself.
I highly recommend this flat if you are a single person or traveling with someone you're very close and comfortable with. The accommodations were perfect for my first trip to Paris.