With this apartment, you are paying for the balcony and the beautiful caldera views.
The inside was okay, but pretty run down (broken chairs, a shower mat that had seen better days, etc.). We ran out of toilet paper, and asked for more and our host told us to go buy some from the market. Which is fine (we aren't divas), but I expect better service for $400/night.
Overall, it was fine - 3 stars - but there are better places to stay in Oia.