Carlotta's place is an amazing location within walking distance of the train station and Basilica of Santa Maria Fiore (Il Duomo). It's also right next to Basilica of Santa Maria Novella, which is a great church to tour and doesn't have the crowds.
Inside, the loft area where the bed is has steep wooden steps that are tricky to climb, so be warned if you have mobility issues. There is also a step in the bathroom that is the bane of all toes. Otherwise the place is great if you are wanting to be in the heart of Florence for a good value.