I was the inaugural guest at Alice's apartment for 5 weeks and I had a good experience. This is a real home, inhabited by a real person, which for me is a big plus.
One can find everything you need in the apartment, including good kitchen, comfortable bed, strong water pressure (a rarity!), a quaint roof deck, beautiful light.
The apartment is a triplex which end up as the 5/6/7th floors of the building. This was good for me, I live in a 5th floor walk-up normally. There is no AC but good cross-breeze from all the windows open, though you do need to shut the windows at night in the main bedroom from the street noise. Once closed, the apartment is silent - great windows!
The apartment is full of character and the immediate neighborhood is excellent, particularly to the north. You could spend all of your time eating, running errands, living life just on Tiquetonne and Saint-Denis. Easy access to tons of transportation, including the RER B from both airports.
I didn't have a lot of communication with the host (perfect for me) but all of it was prompt and thorough, never intrusive and in 5 weeks i had no issues whatsoever, which is more than i can usually say for my apartment in New York!
I would recommend this apartment for sure and would stay again myself, though I do think it is geared toward a traveler looking for real city living and not put off by some lacking conveniences they might be used to - in exchange for the stairs you get a new and positive experience!