The apartment is incredibly tiny, to the point of having to move towels off the toilet if you want to use it (no shelves, cupboards...), and having the bedding *on* the couch when it's not extended into a bed, because there is literally nowhere else to put it. Lots of wasted or just misused space. However, one can get used to this and it is not terrible, just be aware that there is no wardrobe, hangers, nothing. You will live out of your suitcase.
That said, the apartment is not too noisy, considering it is in the center of Paris, and it is literally spitting distance to one of the most connected subway stations - Luxemburg. Across the street are ebikes and scooters, and you can get around easily, go anywhere. The location is absolutely perfect, and if you are of the running type, the huuuuge park is right across the street too. All in all would recommend to anyone traveling solo.