Hard to really evaluate: The first 2 months, no problems, we felt like friends or family, playing board games, having small walks together, talking, we even took a day trip to Elefsina with a rented car.
But when the tourist season approached, Konstantinos behavior drastically changed in a week. He was actually dissatisfied with us but couldn't be bothered telling us until he decided, 4 days before the start of our next booking, that we had to leave. Unfortunately for him, it costs money to throw people out on a short notice, so we stayed but the atmosphere worsened to not telling "Hello" and avoiding each other. We got a bit disillusioned and shortened our stay in Greece.
We recommend staying at his place but not for a too long stay. His mood can be changing