Short version: My wife and I have had many good experiences with Airbnb, but this was by far the best. I highly recommend renting this place, if is it vacant. It is certainly on the top of the list of the apartments we will look into when we are next time going to Paris.
The place: the apartment is large by Paris standards. Because it is a home, not an investment flat, it is decorated welcomingly and invitingly. Viviane's keen and varied interest in art adds to the charm of the apartment. Yet, at the same time, the place was clean and well taken care of. Perhaps most importantly, the bed was the best we've come across on Airbnb. The bedroom is on a quiet side street, which meant my wife and I slept really well. The sofa and chairs in the living room were also really comfortable, and we ended up spending several nights in them.
The location: The apartment is located in a reasonably familiar area for us. The environment is great if one prefers a friendly residential area with excellent shops nearby. It is a bit far from many of the major tourist attractions (but so is any location, as the attractions are scattered in Paris), but we were not interested in those.
Finally, the host: in short, Viviane is simply a wonderful, welcoming and attentive host. Everything was well-thought-through on her side. The communication with her is easy and friendly – and fun! Apparently, she is also a flexible host, as she accommodated our changing plans easily (we needed to make new travel plans as our first flights got cancelled), for which we are grateful.