Grégoire's place was really great. My two friends and I found it bigger than what we expected from the pictures, and it was very bright, extremely clean, and up to date. The location is wonderful, we never felt unsafe and it was (for us) in walking distance to a lot of spots such as the Notre Dame and the Louvre, and with the Luxembourg gardens about a minute away we always had somewhere beautiful to go. There's also a few metro stops really close by (we often used Odéon and Cluny) as well as a few delicious bakeries close for breakfast.
Make sure you know all the details before you arrive, such as which mailbox the keys are located in and how to access them, as well as the code to get into the courtyard. These details were not provided for us before we arrived but luckily someone else was able to help us, and although we never met Grégoire, he replied to my inquires exceptionally quick.
The stairs leading up to the apartment were being renovated during our stay so there was some noise in the morning but it didn't bother us because we were usually up early anyway.