It was an amazing experience from start to finish. I was sad to leave Santorini and especially sad to leave Kalliopi's mother who is such a nice, sweet, warm and courteous person. Her hospitality and politeness goes beyond standards of some renowned hotel chains.

Regarding the apartment, if I had to describe it with one word only, I would say: PERFECT. Perfect and flawless (but that's two words actually). It's spacious, well-maintained, spotlessly clean, well-equipped (fridge, freezer, electric stoves, oven, all the pans and cooking utensils her guests may need... IF they don't eat outside, a quiet and efficient air con, a TV, a reliable and fast Wi-Fi, a comfortable King size bed, a huge balcony, 2 tables where to work - one inside the apartment and the other one on the balcony), etc., etc.
But the most outstanding feature of this apartment is its location: a 30-second walk to the bus stop that can bring you to Fira (and from there to Oia), a 1-minute walk to the nearest supermarket and to an amazing bakery and, last but not least, a 10-minute walk to Perissa beach and its dozens of restaurants.
Talking of buses, I strongly recommend renting a scooter or an ATV rather than taking buses in Santorini. First, buses are seldom on time in Greece - and ferries aren't either, by the way. Secondly and more importantly, reaching Oia by bus took me around 2 hours, whereas reaching it by scooter a few days later took me only 35 minutes.
Should you follow my advice, there are several scooter & ATV rentals a few steps away from Kalliopi's apartment. Some of them are more expensive than others, so do not hesitate to bargain. The same piece of advice applies to transfers from and to the airport (or from / to the harbor): bargaining will probably give you the opportunity to save money.
Last but not least, I must add that Kalliopi (whom I never met in person because she lives in Athens) answered my numerous questions promptly.
To sum it up, this unit is spacious, comfortable, quiet and its location is truly amazing. Moreover, it's pet-friendly. But the icing on the cake, la crème de la crème is the hospitality and kindness of Kalliopi's mother. Just book it and you'll understand what I mean...