We were extremely pleased with our stay at Villa Dio and would highly recommend it to others. Yani, the Manager for the property, was extremely helpful with coordination before our stay, including organizing the taxi transfer from the port to the Villa. He met us personally at the top and had our luggage brought down by one of the bell boys. At the villa, he spent the time required to advise us of all the things that would be relevant for us and was extremely helpful in organizing our activities, including renting a car for the day as well as potentially organizing a guide at Akrotiri.
As far as the villa is concerned, its location is fantastic with unobtrusive views of the caldera, the living space as well as the bedrooms are gracious. It is in immaculate condition and there was daily cleaning service.
In terms of Firostefani, we couldn't have asked for a better location. For our first two visits to Santorini, we had stayed in a hotel in Oia. However, the towns of Oia and Thera have unfortunately been over-run by significant crowds, including the daily ones from the cruise ships who descend on the two largest towns. Firostefani is quiet and peaceful from that perspective, yet there are restaurants and convenience stores which provide for all of one's basic needs.
So, all in all, we couldn't have been more pleased and would highly recommend this property. The only thing that we would have loved to have had in a property of this quality is a plunge pool, as it gets really hot in Santorini at this time of the year. I am told that this may be in the offering in the future.