Ka and Frank were lovely hosts, and excellent at communication (even with this non-French-speaking American).
As for the space itself, the layout is a little bit unusual (as others have pointed out, you enter through the bathroom), but works just fine for a solo traveler such as myself. They have managed to use their cabinet space well to stock the apartment with all the amenities I needed and then some (there is even a fridge and microwave!). If there are any concerns about the bed setup, I can vouch for the mattress being excellent (though I understand this may be a matter of personal preference, so I will mention that I prefer on the firmer side).
As for the location, you may have heard about Pigalle's reputation. Either way you feel about it, this place is perfect - the famed nightlife is a block or two away to the north, but the block the building itself is on is quiet, across from several restaurants, and would be considered family-friendly. In fact, just around the corner to the south is a metro stop for the 12 line, which will take you to all the tourist sites either directly or through an easy transfer to the 1 line.
Overall, the stay was better than expected. As a first-time tourist to Paris who was initially concerned with booking a place outside of the more central arrondisements, staying with Ka and Franck made my time in Paris pleasantly easy and convenient.