We stayed here for four nights and it was far too short! It is an older building and the apartment reflects this, but we didn't mind, plus the location is terrific, so near the Luxembourg gardens and with many places to go to eat. There is a helpfully close convenience store and bakery for the daily baguette. Nai was easy to contact, very nice, and met us at the apartment without commenting on our slightly late arrival due to navigating the metro. The studio is small, certainly, and the bathroom absolutely tiny, but we had no problem with it, fell in love with the place and did not want to leave. The high ceilings add a spacious feeling. Word of advice: don't use the sofa as a depository for luggage or backpacks, it's really comfy and we only found this out the last morning! Stairs do have lights, the switches are lit up in the dark and look a little like doorbells, and this is important because the stairway is very dark when the sun is down. We were there in winter so it wouldn't rise until eight thirty am. The heat was good, definitely enough to keep us happy, and we are both accustomed to much warmer climes.
If ever we have the chance, this is a place we would love to return to.