We had a lovely stay in Florence at Sumiyo's Apartment. The apartment is super cute, well laid out and looks just as pictured. The neighborhood is lovely and the apartment is truly within walking distance of all major sights.
The only thing is that it can get fairly noisy at night/early am with street/car traffic so definitely bring ear plugs if you are a light sleeper.
Sumiyo was wonderful host, very communicative and accommodating to our travel times. It was a pleasure.