We stayed for three nights in Keratókampos. Ostria is a small, but functional apartment. The kitchen is okay for making breakfast and small dishes, but too small and not well-equipped enough for more. A big plus is the washing machine (bring your own detergent) and the sofa bed in the entrance, which is super cozy for reading in the evenings. Restaurants and mini markets are in 25+min walking distance, but it's a nice walk along the coast. However, in late October, many things were already closed. We still found enough snacks and enjoyed the fact that Keratókampos was almost empty and very calm.
We didn't meet the host in person, but the communication worked well and the check-in and check-out were super easy. If you are looking for a calm stay at the coast, Ostria is definitely a good choice.