I have stayed with Ali and Gülnaz before and was so happy that I haven't even looked elsewhere for my second trip to Istanbul. Not only is their service and hospitality unmatched, but they will welcome you with open arms and become an indispensable part to your visit. Kilyos is a fishing village on the shore of the Black Sea close to the entrance to the Bosphorus, and so offers more peace and quiet than the central parts of Istanbul. The city can be reached in about an hour by public transport and in about half hour to 45 minutes by a taxi (costs about 200 lira one way), so still within reasonable distance. The house is located very close to the beach and all necessary infrastructure like stores and restaurants, and everything necessary for the stay is within arm's reach. Kilometers long sandy beaches are famous. Historical sites around the village provide less known opportunities for sightseeing and the fresh fish for exquisite dining.
While close to the beach and restaurants which are open at night, the house is located on a quiet street, so I was not bothered with noise from the outside. I must note that a morning prayer at a nearby mosque begins at 5:30, so earplugs might be necessary for a good night's sleep, but they were provided by Ali and Gülnaz. The apartment is cozy and gives a warm feeling (the maritime decorations are a nice touch at the seaside!), and the bed was very comfortable. While I traveled alone, I felt it might be better suited to a couple - as I was told it should eventually be expanded to fit more people.
Like last time, my visit to Istanbul was a delight, and Ali and Gülnaz's hospitality and care for their guests were essential parts of it. You will do yourself a favor if you stay with them!