We spent 3 nights at Costas' on our honeymoon. It was great!!!
The room was sparkling clean, we had an amazing view and we enjoyed our time together watching the sunset on the balcony. Costas answer fast to all our questions, they have a bit of a water problem on the island and he solved it for us super fast! Costas father picked us up from the port and was happy to return us too.
The house is far for walking from the city, but in Milos you have to rent a house to go around so it's not a big deal.