Pros:
*The location's everything. The view of the Duomo—during the day and at night—will become your strongest memory of this place and makes both coming and going an awesome experience.
*Speaking of location, take the hosts' advice regarding sights to see and/or foods to eat. I walked twenty minutes to Gelateria La Carraia on their recommendation and, despite passing many other tempting options along the way, had the best gelato ever as a reward (the walnut-and-fig). They'll give you a map; follow it.
*Without a GPS-enabled phone, that map will become your bible. Keep it handy.
*With three gates/doors between you and the outside world, you're very, very secure.
*Most amenities provided, even detergent and fabric softener.
Cons:
*Not much room. Two people could stay here, not a person more, and they'd better feel extremely comfortable with each other. This could count as a plus, depending on your company.
*The couch does not feel extremely comfortable. I found it hard to sit on.
*Unfortunately, the chairs at the "dining room" table don't offer relief as they're cheap plastic. Maybe they think you won't do a lot of sitting with so much of Florence to explore?
*Bathroom's small, too, and getting into/out of the shower requires a wee bit of flexibility.
*The washer/dryer combo takes quite a long time to wash/dry. I had to dry my clothes twice as the initial cycle often left them steamed and thus still damp. Divide your time accordingly.
*Some of the setup's counterintuitive. The drying space, for instance, rests above the sink, not next to it. I'd never seen that.
*Bad natural light. Felt pretty dark during the day.
Overall, I'd probably stay again. This place didn't make my time in Florence, but it did make it somewhat better.
Just one traveler's opinion...