We had a great time at Stephan’s apartment, which I would rate as a 5 out of 5 stars. The location is fantastic. 1 minute walk to Notre Dame, 5 minutes to Île St-Louis, 10 to the Marais or St Germain de Pres. There are numerous shops and restaurants within a minute away, as well as a metro stop.
Stephane gives a very detailed overview of the apartment, as does the extensive booklet in the apartment. The flat is spacious for two people, and would be comfortable for 4 adults and maybe a child. 6 adults is doable but would be tight.
The the hottest day of our stay was about 72°f/22°c, so we didn’t need a/c. We didn’t see the setup, but my understanding is that the a/c is portable and only in the main floor with the upstairs bedroom. The downstairs bedroom has a fan but no windows. The windows upstairs are double glazed and do a good job blocking out most of the street noise, except for loud motorcycles or sirens, but we heard nothing in the downstairs bedroom. Of course, if you want outside air upstairs, you will hear noise from Blvd St-Germain, which is about 20-30 meters away.
Overall I would recommend this apartment highly.