(In short: 5 out of 5 stars on everything. I would put in a great deal of effort to stay in their flat next time I'm in florence.)
We had a really wonderful time. It was like staying in our own home. The flat is beautiful. It's nicely furnished, and the kitchen and bathroom are highly functional and nice spaces. Everything was clean and in good condition. They left out delicious little cookies and tea for us, which warmed the experience.
It's an easy 20 minute walk to the main center, and if you're looking to avoid tourists it's perfect. It's a quiet neighborhood with a nice little grocery store and some good restaurants near by.
Christina and Gianni were lovely all throughout the experience. They were responsive and enthusiastic from the day we reserved through the day we checked out. Gianni met us at the bus station and walked us to the flat where he gave us packets of stuff to do and a list of his favorite restaurants.