Mattia was a great host, and his apartment suited us perfectly. Unfortunately Mattia himself was out of town when we stayed but his friend met us to give the keys and showed us the apartment - both Mattia and his friends communication was fantastic throughout.
The apartment itself is a ground floor studio with a mezzanine bed, which was very comfortable, though I'd imagine the spiral staircase could be tricky for those with impaired mobility. Mattia kindly left us some breakfast pastries and water which was much appreciated!
As for location, the apartment could not be better - you are right at the edge of the limited traffic zone so ten minutes walk to visit some of the main attractions. There is ample paid on street parking nearby as well.
We wouldn't hesitate to stay here again if we revisit Florence!