I've booked Cyril's apartment for my parents but I was there during the check-in and dropped by quite frequently. Cyril is a very welcoming and accommodating host - he kindly allowed us to check in earlier and literally walked us through all necessities in his charming apartment.
The apartment is in a posh area - it's 50m away from Invalides and a short walk from the Eiffel Tower. Spacious enough for 2 people, with a bakery and a shop with eco products nearby. The only thing which was a bit inconvenient was that one could literally hear the neighbors walking in their apartments, so if you're a light sleeper or tend to be a bit loud, this place is probably not for you. Parents enjoyed their stay otherwise and I'd recommend this apartment to anyone else.