Great location for a short stay in Florence. It's proximity to the Duomo, Uffizi, Accademia, Ponte Veccio, train station is fantastic. Everything is within 30 minute walk. Tons of restaurants, grocery stores and shopping.
While the unit has a nice view of Giotto's Bell tower, the Basilica and part of the Duomo from the sitting room, fair warning that the bells chime starting very early (7:00 AM) and WILL wake you. Sometimes, they go off multiple times/hour.
Also, I would confirm availability of heat/AC in the shoulder months, it was provided for us , but we had to ask for the key to unlock the unit.
For longer stays, be certain the kitchen has all the amenities you require. While we were able to make coffee/tea and breakfast on the stovetop, the kitchen was not as well equipped as we had expected. In the listing, a stove is listed, but it is a stovetop, no oven. A toaster is listed, but it is a panini maker.
Overall, a great flat in a fantastic location.