I had a great stay at Chiara's place. Few things you should know.
Private bathroom is located in the hallway and is shared with someone else as well as washer / dryer. So it's not exactly private. You will be sharing a shower with the owner of the apartment and whoever else is staying there.
Sleeping quarters are in the home made mezzanine / loft. It's pretty close to the ceiling, do not forget about it when you go to the bathroom at night. Make sure you are able to climb in there.
I could see how the heat could be an issue on some days. It was OK when I stayed, even though I ran provided fan non stop.
The unit is located on the top floor, you can take the elevator if you don't feel like climbing the stairs. The elevator is an experience in itself.
The biggest issue for me was the noise. Because there are several bars and restaurants located directly downstairs, the noise level was insane. It would go on all night. I think it was really amplified by the way it reflects off the buildings nearby. It was more like a rumble that never stops. Luckily I expected something like this so I brought some earplugs. You can still hear some of the noise even with the earplugs in. So if you are very sensitive sleeper be aware of this. With earplugs in after a long day it's fine.
Overall I'm very happy with my stay in Florence and would do it again in a heart beat. Thank you Chiara!