Peter's apartment is larger than appears from the photograph that appears on airbnb.com, which was a pleasant surprise.
The apartment is very nicely furnished and has an excellent collection of books on Firenze and the Renaissance.
It is very well located in the historical center of Firenze, literally around the corner of Piazza Santo Spirito which is one of the lively places in Firenze, particularly in the evening, with many restaurants, less than a 5-minute walk from the Ponte Vecchio and the Uffizi.
One thing to be aware of is that there is (typically slow) traffic right outside the door of the building and the sidewalk is rather narrow, so if you have small children, you must exit first and make sure that no one rushes out too fast.
The staircase to the apartment is rather narrow, but I had no problem bringing a very large piece of luggage upstairs. Communication with Peter and with Isa was very fast and they were consistently accommodating and kind.