This is THE place to be!
Me, my 13 months year old daughter and my parents spent three weeks in Marie's appartment. I had to be in Paris for work reasons. We had a fantastic time there. The area is very central, you can reach the Seine and Jardin du Luxembourg within a few minutes, there are good shops and cafés in the area. This was very convenient for my parents and the baby. The area has many historic buildings, do you can discover a lot just by stepping out the door.
Marie was very helpful and even lent us a highchair for the baby, which was wonderful. Eventhough there are not so many pots and only one toilet, you have everything you need in the appartment: washing machine, two showers, microwave, dishwasher, hairdryer, wifi... Perfect for a longer stay. (My husband even visited us on the weekends and we had enough space.)
If I can ever go back to Paris, I would definitely go back to Marie's place. Merci!