We stayed there for 15 nights from end Jan to early Feb 2019, my 2 kids (7 & 9 years old) slept on the smaller single beds while me and my wife used the double bed room.
Everything was fine as all in good condition, we love the place as we stayed comfortably and it is very safe.
Few things to take note:
1. The 2 single beds are smaller than standard, good for kids.
2. The shower area is very small, bigger size body will have some challenge in movement. There is only 1 shower/toilet combine, not suitable for more people staying in the same apartment.
3. The street outside apartment is very narrow, no space to stop car/taxi during the day. Need to be quick in unloading/uploading bags, the entire traffic stops until you are done.
The apartment location is great, it is about 300m walking to Duomo and right in front of the apartment is a bus stop, you can buy bus ticket from the shop next door. The care taker Vieri is very kind and helpful, look for him as he will try his best to help you.
Very likely we will stay there again next time we visit Florence.