I've stayed in countless Airbnbs this summer, and Francesco's was one of the best. A list of positives:
1) Francesco himself was fantastic. He provided restaurant recommendations (even when I was in Orvieto, another town!), was always super-responsive and easy to reach, was easy to communicate with, and was generally a trustworthy, reliable, and cheery presence. He even went out of his way and helped carry some bags from our car up to the apartment when we were checking in.
2) The apartment itself was beautiful, and was well beyond what I expected. Beyond the view (which we will get to), the apartment was impeccably clean and spotless, the fixtures were brand new, it was beautifully decorated, there was easy elevator access, and it felt super-safe. Air-conditioning was robust in every room, and the double windows meant that it was very peaceful and quiet inside the apartment. There is a doorman at the building during the day on weekdays, and during off-hours the building is secure with a set of double-doors, which each have their own locks. The apartment is on its own kind of private elevator landing, so you won't be disturbed by any neighbours.
3) The view. It's better than the pictures, if that's possible. I didn't expect it to be as incredible as it was. I was even able to see the balcony of the apartment from the Duomo belltower!
4) The location - if you're staying in the Duomo area, this is super central. It is on a side street off the Duomo, and is literally a stone's throw away from the Duomo.
In an ideal world, if I could change anything about the experience, it would be the following:
1) That the showers would be a little bit bigger - but they are totally, totally fine as they are (in fact, we found that having two bathrooms was quite a luxury as it's hard to find Airbnbs like that in the area).
2) The apartment would be a little bit closer to the main entrance doors of the building (right now it takes about 5 mins from the entrance of the building to the apartment, as you have to switch elevator banks). But it wasn't a big deal for me or my family
3) That we had more than one set of keys to the apartment for our family - but that's kind of on me, because I didn't ask Francesco for an additional set of keys upon check-in.
Thanks, Francesco, for being the consummate host! If I ever get the chance to visit Florence again, I hope to be able to stay at your place :)