The location is wonderful and nearly in the heart of the Latin Quarter and near restaurants and bars that are open late (noise-level was never an issue for us so I can only assume the apartment was well-soundproofed). We were only 7 minutes walking to a metro station that could easily take us anywhere in the city and there's a daily Farmers market above the station that's also really nice to check out.
The apartment itself is very well-decorated. The sofa bed is quite large and can easily fit two if needed, while still leaving plenty of space in the room. To access one of the beds in the bedroom you must climb a pretty tall ladder so bear that in mind if you're a rather large or older person or are afraid of heights.
One issue we did come across as that for the people who slept in the bedrooms (not the sofa bed), we all received multiple annoying bug bites throughout the course of our stay (mostly all at night while we were sleeping). I've notified the Airbnb host so that they know to do a proper cleaning of the rugs and rooms and I would hopefully expect this to be taken care of as soon as possible.