Our stay at Federico's flat was wonderful. The apartment itself is big, spacious, light filled and was extremely clean and taken care of. The location is super central and a 5 minute walk to the Duomo, piazza Repubblica and the river. As a native Florentine I found this to be an ideal location to get everything done in just a long weekend.
The only thing I would say you should keep in mind is that if you're staying over the weekend, the street below gets a bit rowdy and cheery. So maybe not recommended for weekend stays for those who want to go to sleep at 10pm!
Grazie for the great stay and great communication Federico!