Yiannis's apartment is fantastic - right in the center of Oia, excellently equipped, and with an astonishing view of the caldera. I dealt primarily with Mario who was very accommodating of our early check in time. He came with another gentleman to carry our luggage down to the apartment (and at the end of our stay back up). He was able to provide suggestions of things to do on the island and was quite helpful in organizing activities as well. He was available 24/7 via whats-app, and when we had an early morning issue (unrelated to the apartment), Mario was quick to respond and to offer his help. It is absolutely essential that you check out the crepe restaurant that he recommends - delightful! The sunset was barely viewable from our apartment, but a 2 minute walk up the road afforded an excellent view. I would stay at Yiannis's apartment again - highly recommended!