We stayed for 5 nights as first time visitors to Florence (we are early 20s)
Pros: great location, 5 mins walk to duomo and 10 mins to Ponte Vecchio/shopping area. Bed was really comfortable and we slept well every night.
Enrico was a great host and responded very quickly to questions we had before and during our stay. Also great location for Santa Maria Novella Train station.
Cons: there are lots of stairs, so make sure you're prepared for that. Although not a problem, the flat is within a larger apartment with 2 other flats sharing a door. There was a minor delay in check in as the bell wasn't working, however after a quick call to Enrico it was swiftly resolved. Not a lot of natural light in the bedroom and no window to open so got a bit hot at night (late September visit) and the only window is in the kitchen but that let in some Mosquitos.
The flat itself was clean, and the cooking area functional, however the flat is a service apartment so you need to but any ingredients you would want to cook with e.g oil, salt etc