The stay was ok. What disappointed me was the location. It said "about 5 min walk to/from (...) stop "Strasbourg Saint Denis". It wasn't! It was between the stop La Chapelle and Gare du Nord, which is much further way from the center and a place that some might consider sketchy (it is ok, tho). We chose this apartment for it's location, knowing we had to climb the stairs to the 5th floor, and then we discovered it wasn't such a good location after all.
The rest was fine. The apartment is really pretty and big. It is also very quiet, with no street noise. The bathroom could be cleaner and there was only used soap, although it said that there would be soap and shampoo. The bathroom is also very small, almost couldn't fit with the door close. It's an old building so do not expect big luxury.
Considering the price of apartments in Paris, and it's size, I still think it's a good deal. The worst it's the stairs, really.
Bonus: It has lots of vegetarian (Asian) restaurants next door.