Frederik is a good host and this apartment is great for a large group. We had 11 but really wouldn't recommend it for a comfortable stay for over 9 people if you all want to use the common area as it really does function as a bedroom if needed. We had a minor water issue requiring a reset of the water pump which we were able to do with text instructions from our responsive host.
Highly recommend for ease of seeing all the Florence sights- its an easy walk from the train station. Just know you are right in the midst of the tourist hubbub the moment you exit the apartment door!