We had a wonderful stay at Marie's place. It is a beautiful apartment in a beautiful setting. The views from the windows are beautiful. The location is on a quiet street one block away from a vibrant part of St. Germain des Prés. We were, incredibly, a 10 minute walk to the Lourvre, Place St. Michel and Sainte Chapelle. Everything else we wanted to do was maybe 20 minutes! The Seine was a few steps outside the door.
The location is safe and charming. Each time we entered, we had the feeling of calm as we entered the courtyard. We are in our 50s and in pretty good shape, I guess, because we did not mind the climb up at all, even with the inevitable moment(s) of getting to the bottom and realizing we had forgotten something.
We were there during the historic heat wave (hottest temps ever for Paris). The a/c was the greatest gift of all. It worked well and cooled off the apartment quickly.
Other notable points: luxurious towels, comfy sheets and comforters, bathtub for 2 (very romantic and relaxing after a day of city life).
Marie met us at the bottom when we arrived and helped carry our luggage up, which I really appreciated as I had a headache and was feeling quite jet-lagged. She also responded to texts immediately and was always very helpful and generous.