My wife and I enjoyed the stay at Ersi Villas very much. The location in Firostefani was very convenient, and less manic than staying in Fira. There are good restaurants close by, and some modest "supermarkets". It is a 10 minute or so walk to the bus station, and you can get along quite well with buses.
Elias offers an excellent buffet breakfast (much more than what is commonly called a continental breakfast, as it includes eggs, ham, etc.), at a modest price.
The rooms are a good size, with terraces. He obviously has a green thumb with plants, as there is luxuriant foliage around. All in all, a very enjoyable stay.