There was the potential for our stay to be marred by unforeseen developments. When we arrived in Italy, we learned that the unit was not yet ready (some repairs were needed and they took longer than expected.) But Samuel and Paolo put us in another unit (also very nice) for a couple of days until our unit was ready. They were incredibly responsive throughout our stay. They even bought us a nice dinner at a wonderful restaurant following the glitch. I highly recommend these guys.
The unit is wonderful. Clean and comfortable. The terrace is smallish, but it's impossible to complain when you are sitting there drinking a glass of wine and staring at the Duomo. Another huge advantage is the elevator. It's not fast. But it beats walking 4 flights of stairs if you have knee problems, etc.
It is unclear if we will ever return to Florence. But if we do, this is where we would stay.