Guido was very communicative before and during our stay, making sure he would be available when we arrived and checking to see if we needed anything while we were there. The location near Santa Croce was close enough to the action without feeling too "touristy" or in the middle of it all. A little bonus is a great pizzeria nearby run by a friendly couple. Guido provided a little booklet of information on the utilities (e.g., how to use the dishwasher, information about the wifi, and a map of some key features of the city) and went over everything with us when we arrived.
The apartment itself was nice. There is no elevator and the apartment is a few floors up, so be prepared when arriving and departing with luggage, and don't forget that you can turn on the lights in the stairwells when you get home at night. A key is required for the door to the street and the apartment door itself has a sturdy lock, so my wife and I felt very safe and secure (the area is perfectly lovely, but it is always nice to have the extra piece of mind).
The furnishings were not the most modern or updated, but they were certainly adequate for the stay. The living room, kitchen, and master bedroom were all spacious and got good light during the day, and the air conditioning units were very powerful, which were a welcome relief for my wife and I as we were travelling in the middle of August.
There are only two negatives I would highlight. First, the shower is somewhat small. I am 6'3" with decently broad shoulders, and I was a little squished between the shower door and the window. Probably not an issue for shorter guys or most women, but if you are on the larger side it will be a bit of a squeeze. Second, my wife and I both found the bed in the master bedroom to be fairly uncomfortable - the mattress is pretty thin and overly firm. Obviously, one can fall asleep on almost anything after a long day of walking the city and seeing the sights, but we both woke up a little stiff in the morning. We only stayed for 3 nights, and I could have seen it becoming a bigger issue if we stayed any longer.
Overall, I think this was a great apartment to stay in. The rate was reasonable, Guido was a very attentive and thoughtful host, and the apartment had the two keys of a good location and good air conditioning.