The place is great. Kostas met us on arrival to show us the apartment and the biscuits/coffee/granola he had left for breakfast. The apartment was cleaned every day and well equipped with everything needed (nice toiletries, fresh towels, coffee machine). Everything in the apartment is a high standard and it was a pleasure to stay there!
The bakery at the top of the town is great for breakfast and coffee (plenty of locals go there) and there are 3 restaurants in the square right outside the apartment, we would recommend Petrino for the Moussaka and Raki for the Souvlaki. The great thing about the apartment is that it's up from street level, so even though you are close to the square and restaurants, if you fancy relaxing you can sit on the terrace with some wine and listen to the bustle and the piano and guitar music from the restaurants!
If you want to explore further then Franco's in Pyrgos is great for food/drinks and to watch the sunset away from the crowds. Petros in Oia is also great, but the crowds here are bigger.
Megalochori is a great little town, but we fancied seeing more so we hired a quad bike from Marks bikes in Perissa (they drop it at the apartment and taxis are expensive). It's also then easier to get to the supermarkets that are too far to walk.
There are so many sights to see in Santorini and this apartment is a perfect base to explore from, knowing you will come back to your own perfect place!