Ali and Jac are fabulous hosts. (I can't emphasize this enough) Communication was quick and super helpful, they have a private link for guests with information about the space, tips for attractions both around paris and near the apartment, and the location couldn't be better - the 69 bus (one of the great sightseeing buses as well as one of the best utilitarian 'crosstown' buses) stops directly across the street, and if you prefer the metro there are 2 stops just a very brief walk from their place. I know Paris well, and have been in and around the 11th but had never stayed there and their tips for neighborhood attractions was a bonus. There is a laundromat a few steps from the apartment, and a franprix supermarket a brief walk away, as well as many lovely shops/boulangeries/bars/restaurants, etc.
as you can tell from the listing, the apt is small - but who cares? you're in paris! In my opinion, you only need a comfortable place to sleep : ) One tip I'd offer is that the floor is tile so a pair of slippers or non-slip yoga socks would be a good thing to bring, as the tiles can be a little chilly at night on bare feet. The apartment is located off an interior courtyard and as such felt very safe.
I'd definitely stay at Ali and Jac's again, and recommend their apt without hesitation. The price is right, the location is fabulous, check in was self-check and flawless, and Ali and Jac go out of their way to answer any questions or offer help in any way you may need. A++