The apartment is in more of a working class neighborhood which we enjoyed. It is 2 blocks from the Bastille opera house, with a metro stop and multiple bus stops right outside the door. It is about 6 blocks from 2 train stations, the Seine, and the Botanic Gardens. It is a short bus ride to Pere LaChaise cemetery and the Marais. One of the buses takes you by most of the major tourist attractions.
The apartment is on the 4th level (counting ground level as 1 and not 0) and accessed by 58 narrow steps, not for the frail or infirmed.

The apartment sits above a busy intersection where construction is on going. The construction stopped for us by 2 pm but the traffic can bottle neck there and create some angry irate drivers. Because of the noise we did not open the windows, but an electronic shade when lowered helped reduce the noise.
The amenities of the apartment were modern with usb jacks, washer ( no dryer), dishwasher, modern refrigerator and a/c. The main bed is a double with a second bed/futon acting as a second double bed. I think 4 adults might be a little tight but it certainly could accommodate them. To separate the sleeping place a pull shade next to the main bed can be pulled down but does not contain the noise like a seperate bedroom.
The cafe right below, Cafe Fauborg has very good french country cooking from the Auvergne region and is quite reasonable in price if you don't want to do your own cooking. Plus there are many restaurants around the Bastille just 2 blocks away.
The a/c unit does make occasional noises in the middle of the night. The electronic window shade did cut down on some of the noise outside. My wife and I are city dwellers so the noise did not bother us that much but other guests may not feel that way.
I think that the host could have spent a little more time talking with us about the area but perhaps
they did not know the area.