We've stayed at a lot of hotels, but on this trip we tried two different apartments booked through Hotels.com. From that experience, the Cosy Suite was quaintly acceptable, with caveats.
The apartment is on the ground floor of an old building, accessed from a courtyard that connects to the street via a large door. It was probably renovated from a larger apartment. The neighborhood is quiet and very convenient to metro stations on two different lines, restaurants, patisseries and stores. What you see in the picture is the whole thing; there is no hallway or foyer, the living/kitchen opens right to the courtyard. Not a problem, but unexpected!
On one side of the bedroom is a toilet with sliding door. The shower and sink is in a small room on the other side. The shower works okay but is so small that it's easy to hit the controls (the water temp is unpredictable anyway). It would NOT work for a very large or overweight person. We will alert management to a musty plumbing odor in the toilet area.
The lighting is nice, and the kitchen with fridge was functional. There's an air conditioner that worked fine. Towels and linens were fine, the regular and sofa beds were firm and comfortable. When the sofa is open space is very tight. There's a nice guidebook and a cute collection of tiny trash cans. Communication with the manager was good.
I can't imagine four people staying here, but if you want to feel like a Parisienne it's okay.