We were met by Mateo, Federico's colleague. He showed us around and gave us suggestions of things to do and where to eat during our stay.
The apartment is just as described and the pictures are very accurate. The location is right in the heart of historic district and the view of the Duomo from the Terrace is fantastic. I enjoyed a gin and tonic there both nights of our stay (there's a fantastic wine shop next door that has a fantastic gin and whiskey selection, in addition to the great wine selection). While the apartment is small, it more than meets two people's needs for a few days in Florence.
One thing to note is that it is the penthouse in a building with no elevator.
I would definitely stay here again.