Our stay at Mariam's place was great! It's a cozy flat, but for three adults (me, my mother, and my uncle) who really only came home to sleep, shower, and eat breakfast, it was perfect. Don't be discouraged by the sofabed - my uncle said it was the most comfortable one he's ever slept on. All three beds have amazing foam mattresses, and we were asleep in minutes.
This was the ideal location, with easy access to public transportation, restaurants, and groceries. It faces a main boulevard, which means street noise. If you're a light sleeper (or travelling with people who snore lol), I would recommend earplugs.
A head's up for those with some limited mobility - the flat is located up one flight of stairs. In typical Parisian fashion, the staircase is slightly curved, slightly narrow, and slightly steep. My mother uses a cane for stability purposes and she handled the stairs like a champ. But others may have issues.
Overall we loved our stay in Paris, and we loved this flat. If/when we return, I would definitely look at this, or another of Mariam's properties.