STAY AT THIS PLACE!!! These are the things that made this place perfect:
1. The location. It's pretty much 10-15 minute walk to everywhere you want and need to be. You're on the same side of the river as all the tourist hot spots, and 10 minute walk to the other side of the river where it's nice to get away from all the heavy tourism spots. It's in a safe place, and you're outside of the heavy mix of it but just close enough that you're not hauling it to the spots you want to see.
2. The building is old and remarkable, but the studio itself is new and has all the amenities of a modern place. NOTE: Italian places start at floor 0 (zero), so this is on the 2nd floor which is technically the 3rd floor. The walk up is not difficult if you're even a little bit fit you'll be fine, it's not too much.
3. LAUNDRY!!!! My husband and I were in Italy for two weeks, and this was our halfway stop on our travels. Having laundry in the studio was the best thing I could have asked for.
4. MARTINA IS A CONSIDERATE HOST! She is quick on communication, and she met us and let us check in a few hours early when our train got in. She leaves great things (maps, suggestions, tourism books) around to help you with touring Florence in the apartment. She also called us a taxi for our departure day to get to the train station. All in all, one of the best (if not THE best) host I've ever had through Airbnb.
We would 100% come back to this place in the future if/when we return to Firenze.