The best thing is the location, magnifique! It is perfect to have 4 metro lines only 7 min away from the appartment. Moreover, the little guide you left about places/restaurants/shops ain the neighborhood is fantastic.
Regarding the appartment, the most important thing is that the big tile on the bath closest to the door is fixed, because it falls sometimes when you close the door (which opens with quite some noise if you don't purposefully close it). Another very important issue is the water heater. It is constantly working ( I doubt it is right) and you can smell the gas, which seems dangerous.

Another less important thing is that we had to buy toilet paper, which is not convenient.

Ah! The bed was specially comfortable, another great thing.