The host was really nice and communicated very well (I cannot stress this enough). However, the accommodation itself had a few big drawbacks.
First, there were spots in the corner of our room (to the right of the window) that looked like black mold or something similar.
Second, the walls and ceilings are cracking everywhere, so the outermost layer is peeling off. In our room, it seems to have been caused by water damage, I would assume, which would tie in well with the presumed mold in the corner. Plus, there were some spots in other locations as if something had dripped from the ceiling at some point in the past.
Third, the electrical outlets are very finnicky. E.g., for some, you have to press the plug to the left for a short while so that the appliance stays on. Or you have to slightly rotate the plug until the flickering light becomes stable (for the bed lamp).
Fourth, all the doors and windows are a bit tough to open/close. Especially for the window, you really have to apply a certain amount of force to pry it open (after having rotated the locking mechanism) or close it.
Fifth, we were barely able to get any sleep due to a combination of an uncomfortable mattress (on my wife's side, there is some kind of wave), a noisy street even in the deepest night, and quite a few mosquitos (just to keep in mind; the host does give you an anti-mosquito device, which, I assume, functions at least somewhat).
Also, just as a recommendation: When in Florence during the summer, you should choose a room with A/C.
Sixth, in the shower, the water (or the drain, we are not sure) smelled similar to rotten eggs and the water pressure was almost non-existent (also, the shower head itself uses approximately half of its activated nozzles due to, I assume, limescale).
On a positive note, the wireless was extremely stable and fast. Also, the kitchen was adequately equipped.
To summarise: The host was incredibly helpful and nice, but the accommodation itself was not as good as we had expected.