I loved Cristina's place! Even if it were not in the center of everything, you can just easily take the bus to the center (around 1.20€ and takes roughly 29mins to the station, the center is in between around 15mins). We caused Cristina a lot of stress since we can't contact her (because we don't have an Italian number) but she was really nice about it. She really gives you A LOT of info about Florence! Would definitely reccomend this place. :)