Gautier's place is excellent! It is in a very lively neighborhood, however, the apartment itself is tucked away towards the back, facing the sunny inner courtyard, so it is very quiet and private. I enjoyed all the diversity of the neighborhood, all nationalities living and working there; it had a gentrifying feel like one gets in some of the hip New York city Brooklyn neighborhoods, plus plenty of night life as well. My favorite street (Rue de Faubourg St. Dennis) was 2 blocks away and you can choose from 3 different metro lines, very convenient.
Gautier himself is a very attentive host and always responded to my questions quickly and his English is very good. While we never met in person, whatsapp and email worked well for us. The place was well prepared and clean, and there's plenty of space too, by Parisian standards (French friends have told me people usually live in tiny studios with efficiency kitchens, so in comparison, it felt spacious to have an actual small living room and the kitchen/dining table was great for eating and doing work too). Be aware that you need to take quick showers, or stop the water partway through, as it is not a tub and drains more slowly. Another small pitfall is that if you have very heavy luggage, lack of a lift i hard the first day of arrival, but this is clearly stated in the description. Overall, great value, comfortable overall with kitchen stuff and fun, interesting decor- I would definitely go back!