The flat is really nice, it's small but lovely. You have everything what you need and a very comfortable bed!!
The apartment is very well located, you have two metro station very reachable. Also the neighborhood is really nice, you are really close to Sacre-Cœur, where you have the best view over the city!
Also the hosts were really friendly and forthcoming; they took great care of us!
We would definitely recommend staying at Laurence&Giuliano's.
Only one thing to add, you hear the metro a little bit, we didn't have any problem, we kinda enjoyed it :-)