My girlfriend and I had a very pleasant experience staying with Nicola.
My stay with him was arranged last minute, but he replied promptly and gave whatever information that I needed. He was full of initiative, asking me what I would like to have for breakfast, and even taking the trouble to find out what train I could take to reach Florence, since I was arriving from Rome.
Nicola drove us to his apartment, but it was also easy to get there via bus 6, which bus stop is located conveniently opposite Firenze SMN Station.
The room and toilet were clean and spacious, and mosquito repellents were provided.
We were loaned Florence guidebooks and given bus 6 timings, which were really helpful.
There was a night where I couldn't find the right apartment to return to (due to the darkness), but a quick call to Nicola did the trick.
All in all, I loved my stay with Nicola and I highly recommend anyone visiting Florence to stay with him :)