The apartment is beautifully presented and has a perfect blend of historical character and modern conveniences. Super comfy bed and lush feeling towels and bedding. The location is wonderful, it's just far enough away from the main tourist sites to be relatively quiet (for Florence) and uncrowded, but a very short walk from anywhere you would want to visit.
Sumiyo is honestly one of the kindest hosts I've met - she gave me a lovely intro to the area when I arrived with wonderful recommendations, and was extremely helpful and caring when I ran into some (not accommodation related) difficulties on my trip. Cannot recommend highly enough and would definitely stay again.