I enjoyed my stay at Félix's apartment. It's located in my favourite part of town, which is central without being too touristy (certainly by Paris standards), and lively without being raucous. It's very close to Pérnety Metro station, and also quite close (7-10 mins walk) to Alésia Metro station; the Metro lines served by these two stations make it easy to access the rest of the city.
Félix was very helpful in his communication. I asked him if he could suggest some nice places to eat nearby, and be provided several suggestions; the ones I tried were very nice. He met me on my arrival, and provided a host of tasty goods; bread and cakes from a nearby bakery, several great (and smelly!) cheeses, fruit, wine, beer, water, chocolate, juice... wonderful!
As described in the listing, the apartment has a somewhat dated interior, but was clean aside from a few minor issues (grouting in bathroom was a little mucky, etc). However it was very characterful - if I fancied living the life of a 1900s absinthe-addled bohemian poet, it would be exactly the sort of place I'd like to live! The week of my stay was very warm (temperatures in the high 20s); but fortunately the apartment has large windows, opening onto both sides of the building, so it's easy to get a decent breeze going through. Lastly, the stairs are steep and numerous - definitely not a place for anyone with any sort of mobility issues!