Katia's place was great! As everyone else has said, the location is AMAZING! It was so helpful to be able to just stop into the apartment for a rest during the day. We also loved using the Duomo as a landmark to find the apartment easily. From almost anywhere in the city, we could just follow the dome home. The walk from the train station is nearly a straight shot and is short and easy. The elevator was also SO helpful with heavy luggage or after a long day of walking. And being on the same street as the Accademia was so helpful! We would go down to the cafe on the corner, Don Nino, in the morning and get some pastries and coffee and have breakfast on the balcony while the bells chimed. Nothing beats that view or those bells. We'd get gelato at night and just walk around the church, listening to the beautiful street performers' music. Sitting on the steps of the cathedral and finishing off our gelato was magical. Just about everything in Florence is super walkable. We could get anywhere in a matter of minutes, so we walked to every museum, site, and shop we wanted to visit with ease.
As others have mentioned, there are a few tiny things that were inconvenient, like slow wifi, no hand soap, keys not turning super easily, and the management company not being a super personal experience. But honestly, none of those things make this spot less than five stars for us! The view and location were worth it all, and none of those things ruined our stay. One tip: bring mosquito repellant! Although we never left the door open, a few must've snuck in while we were going in and out and I got bitten a lot. The pharmacy on the corner charges €10 for itch cream, so bringing your own is helpful! But of course, none of that is the apartment's fault.
Overall, we had an amazing five days in Florence and would stay in this location again and again!