My wife and two teenage daughters spent four nights here, and we'd stay here again.
Louise had excellent communication. When we had questions, she'd responded to our messages right away including organizing a place to leave our bags nearby. This really saved us because our train arrived well before the checkin time. The lockers were right across the street and seemed quite secure. There were only about five of them though, so I would reserve one in advance with Louise if you need one.
We liked the Marais neighborhood. The apartment is located a few blocks from anything touristy, but there are lots of restaurants and cafes nearby. The guide that Louise provided had lots of recommendations, and we really liked the ones that we tried. There's a metro stop a couple of blocks away, but there are lots of museums and parks within walking distance.
The apartment is located one floor up, but there's an elevator if you have heavy bags. There are two bedrooms with full beds, and a fold out coach that we thought was pretty comfortable. The kitchen was small but had everything that we needed to cook a few meals there. There's a clothes washer in the room, which is always handy. Some things we air-dried, and some we dried in a laundromat that was just two blocks away.
I would definitely stay here again.