I highly recommend staying in Philippe's house. I stayed for six nights and would happily have stayed longer. Philippe is a friendly host and a very interesting person to get to know. He is relaxed and easy to get along with. During my study he was respectful of my space in the house and conscientious about keeping the place clean and tidy.
The house is small but cosy. The private bedroom has a good-sized, comfortable bed, a small desk and chair, and a wardrobe space. The kitchen is fairly well kitted out, so you can easily cook at home. The shower and bathroom were fine. The wifi worked well throughout the house.
The house is located in the hills north of Fort-de-France. It's a lovely spot where local noise comes more from chickens than from car traffic. The main drawback of this location -- and for me the main downside of Philippe's place overall -- was the trickiness of going to and fro without a car. The buses come every 30 minutes or so on weekdays (and even more irregularly on Sundays), seemingly without a schedule. Unfortunately, this may be true of most places you would stay in Martinique.
Overall: a great spot with a great host!