I'll keep it short about the appartment: It's easy to find and well connected in a nice neighbourhood; it's quiet and tidy, spacious and so are the bathroom and kitchen - really very comfortable with a few extras of personal style which I liked a lot. I felt at home five minutes after sinking into the bed because you absolutely don't have to worry about anything.
But let's talk about Savino: Savino certainly isn't your average Air BnB host. And neither your average anything - he is really kind, warm-hearted, uncomplicated, funny, incredibly knowledgeable about the city - he can certainly show you around (also in person, if you're nice! So be nice! ;-)) and add a lot of spice to your travel guide.
Speaking of that: he's also an awesome cook (risotto con broccoli e scamorza affummicato...! Damn, I forgot to take some ginger cookies with me). And he's simply been a great help with practically everything from directions to the city to insights into the Italian mentality. In short - he's passionate about hospitality, so there's no better way than to say it his own words: a real Air BnB experience :-)
I guess I also haven't been the average Air BnB visit for Savino - I came here to look for a room for my semester abroad - so I stayed a bit longer with Savino (one week) and I'll also stay longer in Florence, so I'm in for the long-term picture of both the city and him - be aware ;-)
I had not only a good a time but really the perfect start for me here in Italy. If you stay with Savino, you've really arrived in Florence. Somebody else already made the awesome comparison to David, who I haven't seen yet, but I believe that's about the right order - if you come to Florence, you should stay with and get to know Savino. And then maybe David. Not the last reason why I'm really glad to be staying here in Florence for some more months, so to quote Sav once again: You might find a friend here :-)