Incredible experience!
This was the best hostel I've ever stayed in, hands down. Really closer to a hotel/resort, with a refrigerator, personal bathroom, a/c, and beautiful clean rooms that look out over an outdoor pool. The best part is the service provided by Papi, the female who seemed in charge of everything, and her family. In a country that seemingly prides itself on hospitality, she took the cake compared to the other hostel/hotel staff we encountered. Any time we thought of something we needed/wanted, it was almost like she snapped her fingers and had it right there for us.
The one drawback was that it was a bit of a walk outside of Fira (20 minutes), but the bus stops right there and moped/bike rentals are easy and can be arranged through the front desk. I should warn that for some reason, it's not always easy to get a cab outside of Fira. We were warned of this, but didn't have a problem until we were leaving and almost missed our ferry.
I would recommend this place without hesitation to anyone visiting Santorini.