The flat is very clean and comfy: wide bed, fresh towels and linen, very good equipment of kitchen, lot of space, no problem with hot water or wi-fi. There is an elevator, so you don't need to go with your luggage by stairs. Mauro's father Giuliano is a professional host, he gave us detailed and very useful review about apartment, arounds and Florence. The compliment (chianti, delicious cantuccini and big map of the city) was very nice too. Unfortunately we don't drink red wine, so just tasted it. The old centre is a 15-20 minutes walk, not very close, but we love walking, so it wasn't a problem.
But there was a meaning nuisance for all our period of stay: noise. In addition to a rather loud noise from the road the apartment has a very loud neighbours from the top who makes a lot of noise late at night and whose pet just deafeningly scratching the floor with claws. It was difficult for us to fall asleep despite the fact that we were very tired, so we had to use earplugs. Pay attention to this if you have a sensitive sleep.
All the rest was great, Florence is amazing city and our staying here was unforgettable! Thank you very much!