We stayed for a week in the apartment and couldn't fault it. Eugenia & Karen were perfect hosts and left a few extra items which were much appreciated. We used one of the restaurant recommendations on our first night ZaZa's and it was just as described. That was really helpful to first time visitors. We also used one of the supermarket recommendations and always shopped at this one, never feeling the need to try anywhere else.
The square outside is very busy at night and you can hear some noise in the apartment but we never felt unsafe. In fact on many nights we noticed that there were children of all ages amongst the adults so it was just a place to hang out.
Location wise the apartment is walking distance from most of Florence and is especially useful for the train station.
If I visit Florence again in the future I wouldn't hesitate to book this apartment again.