I was in Florence with a group for a wedding. 10 of my friends stayed for 3 nights and had both Giotti and Michelangelo units (same floor, right next to each other) for ourselves.
The best area hands down! Location is great whichever part of the city you go. You can walk to any of the points of interest-- Doumo, Piazzale Michelangelo, Ponte Vecchio, Academia, etc.
The apartment units were immaculately clean and functional. We had coffee amenities, breakfast starter. I myself stayed on a pullout couch which was very comfortable, the mattress was just right the firmness I wanted, the sheets good quality.
Salvatore, the host was extremely helpful. He waited for us even when we arrived later than when we advised him. He was thorough when he gave me a tour on the units. On a map he oriented me about the location and gave suggestions based on what we wanted to see/experience. On departure, he arranged for a taxi to pick us up, bought me an espresso before we took off to leave.
The best airbnb experience so far!