The location is just perfect, even better than I expected. A safe and beautiful neighborhood, very clean and quiet, close to the center. The windows open onto the patio, so no noise from the traffic. A lot of restaurants just near the house, 2 supermarkets and a grocery (I suppose, 24/7? We've found there all we needed upon arrival). 2 metro stations and several buses, so no problem with public transportation.
The studio itself is beautiful, clean and very comfortable. There is a coffee-maker, dishes and all the small things one needs (salt, oil and so on).
And Nathalie is a very nice person, helpful, very good hostess. There was a problem with the WiFi, but she has arranged a free access to the Internet with her personal ID and a password, so we were all set.
In one word - perfect. Definitely, I'll be happy to stay here the next time I'm in Paris.
And a small additional thing, just in case somebody would be excited like I am: it's the house where Chopin used to live with George Sand for 3 years.