My wife and I just finished our stay here, and absolutely loved it!
The apartment is centrally located, just north of the Duomo, and everything you'd want to do is within walking distance. And, if you don't feel like going outside, the terrace has an incredible view and is a perfect place to relax.
Alessio made everything very easy -- he accommodated our check in time, and helped coordinate a cab when we checked out early. He also gave us good tips on places to eat and sights to see.
The apartment is at the top of quite a few stairs, so be ready for that. We also found Florence in general had quite a few mosquitos this time of year, so pack some bug spray for your days in the city.
Overall, we had a fantastic stay and hope to come back soon!