We stayed in this apartment for three nights. There is a lovely view of Santa Maria Novella church, which could not have been more central. Only 15 minutes walk from the main train station, Santa Maria Novella. Federico checked us in and he was very nice and chatty to us. The apartment was nice and clean and we enjoyed playing cards on the terrace in the evenings.
The bells are very loud but it is to expect when you chose to be so close to a big church!
There are 82 steps to the apartment and no elevator, so I would recommend a backpack more than a suitcase. It was good exercise though! I think it helped us not put weight on those days. :D