This flat's location can't be beat.
It's great for a short stay in Florence, max 2 people, because it is a very cozy studio. Some small cosmetic faults that aren't that big of a deal are noticeable in the apartment, and if you're a light sleeper, be aware that the walls are a little thin. We counteracted that by making sure the heat or AC was on at night, which acted as a good source of white noise.
Overall, the flat is good. Incredibly centrally located -- and, you'll be spending most of your time outside anyway! Definitely book if location is a top priority. (Plus, there's an AMAZING gelato shop, right downstairs.) Oh, and the Duomo is down the block and visible from your window!)