Our experience was similar to many other guests of Kostis. He was an exceptional host and we had a wonderful stay in his apartment. He provides an array of provisions in the kitchen and fridge that go well beyond what we would have expected.
The apartment itself is spacious, very clean and well presented. The beds were comfortable and everything worked as it should. The roof terrace is special.
We loved the location, close to the main sights and Plaka but in a relatively quiet street. The area feels very safe day and night. There is a great bakery literally around the corner which Kostis will likely point out. Their products are excellent. Likewise in the side street just opposite the bakery is a cafe/bar that serves coffee and juices in the am and wine and beer in the pm along with a range of cheese and meats.
Kostis genuinely wants you to enjoy his apartment and your stay in Athens. We certainly did.