Louis apartment was absolutely wonderful. Newly renovated, spotless clean, super comfortable, and pretty, perfectly located in a safe and quiet area just 100 meters from the stairs that lead to the Sacre Coeur. There are plenty of shops, cafes and restaurants within a few steps.
Two great things as a woman travelling on business: 1) I always felt safe walking to the apartment, even when coming back late at night and full of photographic equipment. 2) The wifi is very fast.
If you want to spend a few great days in Montmartre, don't hesitate to rent Louis' apartment.