I had an excellent stay at Niccolò's place in Florence. The place itself was awesome – the AC works well, the internet is fast, the bed is comfortable, the place is clean, quiet (nestled inside of a quiet square), and spacious, and the building even has an elevator (nice bonus). After spending 4 nights in Florence, I'm convinced the location can't be beat; the apartment is steps away from Palazzo Vecchio & Uffizi Gallery and a couple blocks from Piazza della Reppublica and Ponte Vecchio).
As a native Florentine, Niccolò gave me a great set of tips on places to eat and things to do. The checkin process was smooth – Niccolò met me in person and gave me a quick overview. He was very responsive and helpful. Overall, the value I experienced was excellent; I hope to visit Florence again and will seek out Niccolò's apartment when I do!
(As a side note, if you're departing via Taxi (and don't speak Italian), plan ahead and give yourself a bit of extra time; the taxi dispatchers are impatient and need an exact address for pickup!)