Guillaume is very responsible, quick in reply host (very grateful for that!). The appartment is good, safe, clean and close to metro.
Just the region it is placed in is pretty weird, wouldon't recommend to go there with a kid like I did. Montmartre is actually much further than 12 min walk, it took me 10 min by Uber to get there from my place ;)
All the other points are good and fair.