I was very happy with the place for my six week stay in Florence. Great location in the Oltrarno away from the crowds but in easy walking distance to all of Florence. Within a few blocks of many bus lines when going farther afield than the centro storico. Very clean and comfortable place and easy and fast communication with the host. It's a 2nd-floor (3rd-floor in US) walkup.
There are great restaurant options all around but the kitchen was also well appointed - refrigerator/freezer, microwave, toaster, kettles, stovetop, pots/pans, glasses, dishes, cutlery, dishwasher.
I stayed after the summer heat so did not need to use the A/C too much, but when I did it worked very well and I imagine it would keep the place nice and frosty in the summer.
The Wi-Fi worked perfectly the whole time and had plenty of bandwidth at 100Mbps download (I don't remember the upload bandwidth, but it struck me as normal for a 100Mbps down link).
I wondered if I'd regret not getting a place with a washing machine, but the multiple laundromats within a block or two worked out perfectly as long as I didn't visit on Saturday mornings when everyone seemed to visit at once.
The street is a generally pretty quiet and low-traffic residential street so noise was never a problem. The windows also do a nice job of sealing out noise when closed. There is an enoteca on the corner across the street, but I never noticed any noise at night with the windows closed.
I would definitely stay here again when I'm in town.