Marinos was very nice and helpful. He even helped us to book a car in Milos for a good price (55€ per day). The Location is right in the Center of plaka; which is nice for restaurants and the sunset. there is no beach so you need the bus / Car.. to go to the coast but the bus comes every hour. The aspect we will keep in mind the most is the lovely host, flexible check-in/out and the location.
What we did not like so much was that the AC did not work (which is not too bad as the flat does not get too hot as it is quite dark what is positive in this case :)), there is really no connection at all on the phone and no WIFI. You need to walk 2 minutes to get connection. Apparently the connection on the whole island is not the best. The shower curtain should be changed as it is mouldy and the smell in the flat is a little weird; it smells like the walls are wet.
One thing to know is that there are quite a lot of cochroaches around the apartment and in the whole city but this is of course not the owners fault. The apartment itself seems to be impermeable for them as we did not have a single one inside the apartment :)
The towels and bedsheets smelled very good and we had a bottle of water in the fridge when we arrived :)