Three of us stayed for three nights at Kostas's place. Overall it was OK. The place is in a great location---easily walkable to shops, restaurants, and sights. The building and neighborhood felt safe and parking on the street was easy. The apartment itself, though small, has the bare necessities for a short stay; a highlight is the balcony, which has a very nice view of the surrounding area.
However, we had problems with the hot water after the first day and the lock on the balcony door is broken. Kostas tried to help with the hot water but was dismissive about the balcony lock---seemingly an old problem based on past reviews. This was not OK with us given that the balcony is easily accessible from the next-door apartment.
Also, the place could really benefit from more attentive cleaning and some basic items to make it more comfortable. The sheets, towels, and the toilet/sink were very clean, but the floors and stove area were not. A bunch of little things were lacking: no kitchen knife or cutting board for food prep; no kitchen towels or paper towels; no cover over the bare eye-level bulb in the bathroom, or shelf over the sink; no bathmat. There was no bottle of water for us when we arrived, which has been standard at every place we've stayed where the tapwater is not drinkable. These are not *critical* things, but it just felt bare-bones.