Location - you can't ask for more. Walkable to almost all of the important POIs in Florence. Very close to the Duomo, a lot of cafes and restaurants. If you have luggage and are coming in from the train station, take a cab. Should be around 12 euros. We found a nice cafe - La Badia open early for breakfast.
Apartment was very clean when we got there. All instructions provided. We loved the fact it had a washer, especially after a week through Italy in August.
Guido was super responsive and helpful to any questions or messages. He even booked us a cab for getting us back to the station.
Overall - highly recommended. We would really love to come back here on our next visit.