Anne-Constance's place turned out to be even better than I expected, I think the room is big for 1 person and would comfortably host 2 people as well. You get to use a big bathroom for yourself, and even an extra storage room if you really have too many stuff and don't want to put them in the room. There's a big window facing the street providing natural light and wind, but as the apartment is on a big boulevard, it can bring in street noise day and night too. Although it's not a problem for me, it may be for light sleepers.
Check-in is very easy & smooth, Anne-Constance and her family are all really nice people and made me feel like I'm at home during the stay. Transportation is very convenient too, there is a bus stop just downstairs, and 2 metro stations that can be reached in 1-3 minutes on foot. (If you have big luggage, it's better to arrive at Michel-Ange Auteuil station which has escalators going up.) All in all, it was a pleasant stay, definitely recommended!