Pierre has an amazing studio close to the center of Paris. Connections are super easy from there to anywhere. His flat was spotless clean, he was very quick to respond to any questions, and although it's his personal flat, you get a great feeling as a guest.
The only thing I'd like to point out, and this is NOT Pierre's fault, is that there's been some drug issues in the neighbourhood nearby (Stalingrad). This seems to have happened mostly during covid times, so hopefully it'll get better quickly. We never felt unsafe around the house - only when we travelled to see the Luxour Cinema at Barbes, which is a few stops away. However the walk from Barbes to the house was a bit nerve wracking, as the neighbourhood around that area has really gotten into some trouble with drug users.
At the same time you are right next to some of most exciting shops around Paris, and you can walk down the Canal Saint-Martin which is one of the nicest hipster areas in Paris which is full of amazing shops and places to eat. Belleville is also nearby and again it is a wonderful area.
Again - I highly recommend you stay at Pierre's if you want a nice studio close to central Paris. This review is being written in September 2021 so if it's been a while, perhaps the situation with the neighbourhoods nearby will change rapidly.