Regarding booking.com, when I was looking for a place to stay in Paris, and found the place called Luxuous 4 rooms apartment in Marais where we actually stayed at the end, i only wanted to first contact the owner and ask a couple of questions, read reviews but i could not. When booking.com offered me to reserve the place for the requested dates, it turned out that i can only book it without canceling it even on the same day of booking, only if i paid a large part of the fee. This is unacceptable and it is against the law of consumer cancellation policies of the EU: http://europa.eu/youreurope/citizens/consumers/shopping/guarantees-returns/index_en.htm
After I made the reservation, that turned out an actual booking, i could read reviews that clearly stated that the place is not the cleanest and nor the most comfortable for a family of 5. This is why booking.com's policy has to changed. Myself is not willing to use their services again if this policy is not modified.
So we got stuck with this place, since we had no other choice. Now about the apartment:
The place has a wonderful location, close to the metro, to Velib (bike) stations, close to supermarkets. It is on the third floor without elevator, what was still ok for us. However the apartment itself can not be called a "Luxurious" place. It is a place with charm, it has some special Parisian touch, but not luxurious at all. The bathroom needs immediate refurbishing and the place needs a good cleaning. The beds are small and uncomfortable. During the hot season sleeping with windows open is impossible due to the noise from the main road and it has no air conditioning. If someone can put up with these conditions, a stay in this charming place can do the work of having an accommodation in Paris.