This is a good apartment, in a convenient part of the city. We used Gare d'Austerlitz as our main local metro stop, and there are many electric bike and scooter locations all around. The river is close by, so you can rent a bicycle and cycle along the river to go past Notre Dame, the Louvre, and on to the Eiffel Tower.
The Jardin des Plantes is right across the road, and you can walk through the park to get to restaurants, Notre Dame, etc. The park itself is big and peaceful, so makes a nice break from the noise of Paris!
There are many bakeries and food places around the block, and Rue Mouffetard is close by with lots of different restaurants. Many local children and teenagers hang out in this area, and it felt very safe and friendly.
The apartment overlooks the National Museum of Natural History. In the evenings, when we returned to the apartment, we opened the large window, sat down, and watched the museum and the traffic go by. It's very relaxing.
The sofa bed was very comfortable, and I had no problems sleeping on it for 5 nights.