The apartment has plenty of light, is in a reasonably modern building with all expected amenities, including a fully-equipped kitchen, and is immaculate and (unlike so many airbnbs) mostly unencumbered with the owner's personal effects. Claire, the owner, met me in person, came to see me out, and could not have been friendlier or more helpful, including with above-and-beyond help on some personal logistics that proved invaluable. I felt at home from the first minutes.
The St.-Ambroise neighborhood is trending but not hipster, harking back to an older Paris of small shops and restaurants, with plenty of local streetlife and few tourists. It's an easy walk to the Bastille hub and to other key areas, and the Métro and bus links are first-rate. Claire has developed a list of excellent recommendations for local restaurants.
I stayed for nine days and would gladly have stayed longer. Highest recommendation for a hassle-free, well-supported stay in a great Paris neighborhood.