A great place, the location is the best in Florence. Best pizza place in Florence beneath the apartment, and the former Jersey Shore employing pizza place is opposite the apartment (who actually sell a really decent pizza as well). Also, the house is right in the middle of all the main landmarks (Uffizi just 1 minute away), while the shopping and posh shopping areas are a street to the west and the going-out area is a street to the east.
The apartment itself is very clean, with beds made and all, and you will be met by Gabriel who will give you a lot of inside information about the city and surrounding area. The sleeping couch is very comfortable, you can consider it as a regular two-person bed. Only thing you may consider is that this apartment is in the middle of the city center, with people walking through 24/7, so it can be difficult noise-wise if you are a very light sleeper. We had no such issues though. All in all, we had a really pleasant stay at this apartment and would recommend it to anyone.