Olivier and Emmanuelle were very helpful when I asked them about trains due to the ongoing transport strike, or finding things in the immediate area. And Olivier helped me with my heavy pack up the stairs, etc. They also allowed me to take a couple of towels to the swimming pool so I could go for a swim (that was a culture shock experience...! as an Australian).
The room is nice, with a small bathroom attached, both on their own floor on the way up the stairs. The bed's comfortable. The shower's a bit uncomfortable to use - you have to hold it up, so washing your hair's a bit awkward. (This might be common across Europe/UK...?)
So, best for a short stay as others have said. A plug for the sink would have been appreciated just so I could wash a few small items without having to find and negotiate a laundromat (as a non-french speaker).
The setup is that the hosts are living separately in their own space; there is not really anywhere to interact with them in a friendly way. It feels like they are offering an efficient, limited, set apart style of hosting. I admit that due to my own experiences just prior, I would have appreciated a bit more friendly interactivity, because I'm a non-french speaker and everything was challenging the first two days there. I felt a bit sectioned off and left to myself.
Also, it was a little bit awkward not being able to eat any food in the house at all if you have limits on what you can eat - ie you can't have food in the room (I understand this) but you don't have any access to the kitchen or any other living spaces if you just want to cut up some fruit or keep milk to have with cereal/tea/coffee etc. (There is tea and coffee supplied upstairs with a kettle, but no milk.)
The location was fine - close to the subway. I got the impression it's more of an immigrant area, also with more homeless people also than other areas. This was fine, not a complaint - good to see the reality of Paris on your visit, and I felt safe. I enjoyed Cafe Bolivar around the corner while I was there.
Thanks Olivier and Emmanuelle, and all the best.