We thoroughly enjoyed our stay at Massimo's. His apartment is beautiful - modern, spacious, comfortable and well-stocked. It's a bit removed from the city center and its main attractions (approximately 20 minute walk to Duomo, Mercado Centrale, Uffizi, Ponte Vecchio) but the route is pretty direct; we walked everywhere during our stay.
Massimo is meticulous and willing to help. Upon check-in, he gave us an extensive walk through of the apartment and its features. He recommended a number of restaurants and activities and provided us with a really helpful map of the city. He also made dining reservations for us. Massimo is also very outgoing - he greeted us with a bottle of wine and a nice card, and was very understanding when we were late for checkout because of a hang-up with our rental car.
We loved Florence and would definitely stay at Massimo's again.