I really enjoyed Raul's place, and will definitely check its availability if I ever make it back to Florence. I liked the location — not touristy, and relatively quiet, but easy to find and an easy walk from all the most famous spots.
Raul met me when I arrived; he was very friendly, made sure I knew how to lock and unlock the doors (which I really appreciated), went over everything in the apartment with me, and gave me a tourist map, marking it up with our location and the locations of a number of sights in Florence.
I spent most of my time out exploring, and ate all my meals out, but the flat was well appointed for those who wish to prepare their own food. (Stove only — no oven.) The bedroom underground is very dark — I liked it, but in the morning I had no sense of time. Cell signal was iffy for me (roaming with an EE SIM from the UK) on the main floor and non-existent in the underground bedroom. The wifi was good on the main floor, but did not reach the underground bedroom. My two-pronged travel adapter did not fit most of the power outlets (the prongs were too thick) so I purchased another adaptor nearby for €1 (and Raul had left a USB adaptor as well) . Most of the time the apartment was very quiet, but a few times people on the stairs or street were loud, as were a few motorcycles. All in all, I had a great stay and was very happy staying here.
(Sadly I did not get to climb the dome of Duomo, as it was sold out for the next few days, but the view from the bell tower was great — I kept thinking I had made it to the highest accessible level, but it was obvious when I finally did as there was nothing more above me. My favorite Florence spot aside from the most famous ones was the Basilica San Miniato al Monte — the view over the city was beautiful, and the cemetery was dramatic.)