I greatly enjoyed my stay at Marianna's apartment. It's clean and spacious, and has everything you need. The location is very good: not in the center, so it's quiet and calm, but with cafes and supermarkets near. It's 3 min walk to the river. The center is about 25 min walk, it's good for a long stay, when you have time to spare to just enjoy the city.
I didn't meet Marianna, but she was very friendly and welcoming and replied really fast to all my questions. Her dad came to show me around the apartment and he was very nice and helpful.
I can safely recommend Marianna and this apartment for an enjoyable stay in Florence.