I didn't meet Nathalie, but Julien checked me in. He was a bit late due to a traffic block, but was continuously communicative, and a pleasure to interact with. Nathalie was communicative via messaging throughout my stay and before it.
The place is typical Parisian. It's very cosy, and beautifully furnished. It felt exactly like home. It's spotless clean and fully provisioned. The building is very safe and in a very connected area. I sensed a bit of noise during the night with open windows, but I had to close the windows anyhow due to the temperature. The WiFi was a bit flaky on the first day but Nathalie immediately responded that she was already in touch with the provider, and the problem went away the next day.
On the whole, I had an excellent experience and I would return to Nathalie's place if I come back to Paris.