Spacious apartment, exactly as described. We were there with a family of 6 and had enough room. The 3 ensuite showers are really good to have. The combined living room/kitchen is a great spot to come together.
The location of the apartment is great, the railway stations are literally across the street. The market hall one block away is an amazing place to buy food and also to have lunch/dinner. The location around features a multitude of shops and restaurants. If you don't mind the distance you can basically walk to the center through Rue du Faubourg Saint-Denis, and find anything you can think of on the way.
All three bedrooms of the apartment have windows to the boulevard the Magenta and this road is never empty, even on a Sunday night, with a lot of buses and police sirens. This should be kept in mind by anyone who has a light sleep.
For a late November weekend, the heating was working fine. I cannot comment on the AC, but I would never try to sleep with an open window.