My wife and I largely enjoyed Frédérique's place. The room itself is a good size, and the bed is one of the only true king size beds I've encountered in Europe. The bed was solid and comfortable, though note for those who are tall and/or have back issues, it is quite low to the ground. The room was quiet except for the weekend, when the apartment block gets very lively. Pack earplugs for those nights if you need to sleep early for a flight the next day. The bathroom was large, the shower pressure was great. The home is far from the metro but close to buses, which are as easy to take as trains (and use the same tickets as the metro). The neighborhood is wonderful, it is close to la Butte aux Cailles, which comes alive at night. Note that you are given only one key and you must use it to both enter and exit, so if you are a couple, you have to both leave and come back to the apartment at the same time. This was a bit difficult for us, as I was there for a conference that met early in the day, and my wife would have preferred waking a bit later to go for her croissant and espresso.
The one issue we had was that we did not generally feel welcome to use the common spaces. We knew from the listing that the kitchen was off-limits, but it was a bit patronizing to have it (literally) cordoned off, as if we couldn't be trusted. We also knew we could not take meals in the home, but we did not realize this extended to having a bit of bread and cheese either at the table in the common area or in our room. When we were told we could not eat anything in the home lest we incur additional charges--which was in itself puzzling, as a rental is not considered a bed and breakfast in Paris unless the host serves meals to the guests--we had to leave our baguette and cheese downstairs until we left later to eat our bread and cheese outside on a cold, rainy day.
Overall, Frédérique's place is to be enjoyed by people looking for a nice place to sleep and shower in Paris without paying the exorbitant hotel prices, not if you are looking to spend any leisure time in the apartment itself. For that, it is likely the best value around.