We stayed in Philippe's studio for 5 nights. It is in a good location, one block from the metro (Jusssieu) near the Latin quarter, so many dining options are in walking distance (rue Moufftard).
Philippe was very nice and accommodating, welcomed us when we arrived and brought us a nice typical French breakfast every morning (right to our doorstep!).
The studio is in a nice building with a courtyard, up one flight of stairs and the windows face a quiet back street.
It is just as described, small but has everything you need.
A couple of downside points: the floor is hardwood and it squeaks pretty badly so the first night was challenging because every turn in bed was clearly heard. This was solved by moving the bed a bit to a less squeaky spot. Also, the bed itself is actually a futon, which we felt should have been mentioned. As for the bathroom, it is tiny and taking a shower was a challenge (we're both pretty short and not very big...).
All in all, this is a decent option for this area of Paris.