This was our first AirBnB disappointment. The sitting area looks wonderfully inviting in the photos and artfully staged but in reality we found was a rather dark and the sole futon was covered in a cheap comforter - not a place we felt comfortable spending time in. The shower was mouldy, the bathroom a very narrow galley, and the air conditioner leaked large volumes of water when turned on. The vinyl floor tiles are curling up from the water damage. The loft bed which looked kind of fun in reality difficult to access and on quick inspection lacks a good quality mattress.
Looking back at the positive feedback from people who have stayed here it is fair to say it is partly about expectations. We did not feel comfortable staying here and moved to a hotel, not wanting it to negatively affect our experience of Florence. However this place is inexpensive relative to other apartments in Florence and is close to the train station. For student backpackers this might be the place for you.
The kind woman who opened the apartment for us could I think tell that it wasn't a good fit for us, but this apartment is one of many owned by an agency and there was little she could do other than pass along our feedback.
I genuinely hope your experience is better than ours!