I stayed at Cristina's house for new year's vacation.
The room and bathroom are comfortable.
The location is great:
1) 5-10 minutes walk to the train station.
2)10 minutes walk to the DUOMO.

Cristina was very effective/kindly made suggest to local restaurants and every information I needed for exploring the Firenze.

The only thing have to note is as Cristina wrote in the house rules:
- have to climb the stairs up to the 4th floor.
- there is obviously some street noise in the morning.
But you will have the best location to explore Firenze.