Very good location where you can pretty much walk to all the main attractions of Florence. Luca who helped us with the check-in was very friendly and helped with any questions we had as well as recommending a list of restaurants.
The flat itself was really nice with a lovely view of the Duomo. It had all the necessary amenities and we didn't have much issue staying here for a week.
My partner has dust allergies, and although it may look quite old, he had no problems staying here which indicates that the flat has been cleaned and well kept.
A few things to bear in mind if you choose to stay here, although weren't too much of an issue for us:
As many others have mentioned, there are quite a few steps to get to the flat. If you have a lot of large, heavy luggages, you may struggle a little bit towards to top due to smaller and narrow steps.
The flat is above a bar, therefore there can be some noise you can hear during the night, so reccomend bringing earplugs.
Also with noise, in the early morning you will hear the tower bells ringing every hour, so without earplugs, it may wake you especially if you decide to sleep in.