This place has one of the best locations in Paris! It is a 5 minute walk to the Gare de Lyon which has the metro, trains and buses. There is a bakery right on the corner and a small grocery store between the apartment and the Gare de Lyon. Getting around the Paris area was very easy because of the quick access to the Gare de Lyon.
My mother and I stayed 3 days. Christian was so kind to meet us at the Gare de Lyon when we arrived by TGV. He escorted us back to the apartment and showed us some helpful things along the way. The apartment was great and was a great place to come back to every evening. It is a studio apartment with no bedrooms. The couch pulls out into a queen size bed. This is their personal apartment so it was like staying in someone's home.
A few things to be aware of:
1) No wifi even though it was listed in the amenities. There may have been wifi but Christian did not know how to access it. This may be fixed now so you would need to message Christian. There was a Mac in the apartment so I could use the internet on their computer.
2) No AC or fans. Fortunately the weather was in the high 80's and low 90's so it was fine. The day after we left, Paris was 100 F. I would have been uncomfortable in the apartment. Unfortunately, AC is not as common in France as in the USA. Most of the hotels on the road across the street did not have AC.
3) The building itself was extremely quiet. The large window in the living room right where the couch/bed is located is directly across the street from the entrance to a hotel. Since the apartment is on the ground level everyone coming out of the hotel has a direct view of the 'bedroom'. If the weather had been cooler and the curtains/windows shut, this would not have been an issue at all. I felt very exposed but this did not bother my mother.
I would definately stay there again in the fall/winter/spring if there was wifi. The location was perfect for us since we were arriving by TGV. The other great thing about the location is that Air France has a shuttle to the CDG airport that picks you up right in front of the Gare de Lyon and is non-stop. It took us about 30 minutes to get to the airport.