Francesco was an outstanding host - responsive, kind and accommodating. I was a little early on schedule and, since the apartment was ready, he came to let me in so I didn't have to wait around in a café with my luggage for 2+ hours. He also recommended a couple of restaurants that we actually went to, and they were excellent.
The apartment itself is also really great - superb location right on the main market square, very quiet for being so central, with a modern design feel and spacious interiors. The kitchen was overall equipped for our needs (coffee and simple breakfasts), and the beds were comfy. There is no lift and the flat is at the top of the stairs, but this is often the case in Florence. I would definitely recommend both the apartment and the host!