Our 5 night stay in Fede's apartment was fantastic. Fede was really accommodating in meeting us late in the evening, helping us up the stairs with our luggage (yes there are lots of stairs), and had a marked up map ready to show us with his recommendations for food and wine. He was also really quick to respond to texts/emails, and helped us book taxis as needed.
The apartment is charming. Of course the view is to die for, but the whole place is spacious, comfortable, and homely. It is an old building so you have to accept that there are some little quirks, but if you book this apartment you wont be disappointed. Great location too, around the corner from Ponte Vecchio and walking distance to all major sites. Would stay here again in a heartbeat.