My family of two adults and three teen-age children recently stayed in Hamid's place for five nights and it was wonderful. Florence can be hot in the summer, so I was a bit worried about that, but we were very comfortable in his apartment. Each bedroom has a mini-AC, and there's one AC unit for the living room/kitchen area. But honestly we didn't use that one very much, because there were comfortable breezes blowing through the open windows in the evenings.
The location of Hamid's place is perfect: a 10 min walk to Duomo, 5 min to the Accademia, 5 min to the Mercato Centrale, 20 min to the Uffizzi, and 15 min to the train station. If you've never been to Florence before, you'll be surprised by how easily walkable it is. We were there for six days and didn't use a taxi at all. The nice thing about Hamid's apartment is that it's a little bit outside the "tourist zone". Also, there's a grocery story very near by, so it's easy to stock up on essentials. Hamid has a full kitchen for cooking whatever meals you want to cook.
As a host, Hamid was wonderful. He was quick to respond to questions (sometimes late at night) and gave us lots of helpful advice about things to do and places to go in the city. We were very tired and jet-lagged when we arrived, but he greeted us with warmth and kindness and showed us how to make coffee, Italian style.
As other reviewers have noted, you have to walk up several flights of stairs to get to Hamid's place, so keep that in mind. There's a little bit of city noise if you leave the windows open, but hey, Florence is a city! The water pump (which refills the tank) sometimes makes noise at night, but Hamid can show you how to turn that off. Other than that, no complaints at all. It was a great stay, and we will definitely go back on our next visit to Florence!