Serena is a very well organized host. The flat was absolutely clean and fancy. Location wise it is in the heart of Florence, ideal for sightseeing. You are at the dome within minutes walking.
If you arrive with a car inform yourself beforehand! Driving in the inner city is no fun at all and additionally you need special permit. If you don't have it and are filmed entering each occurrence costs you 104€ (year 2019).
One drawback of this apparent is that the wall to Serena's other apartment is very thin (and there is even a connection door). Depending on the other guests it can get rather loud. Take earplugs with you ... just in case.