I staid for 3 days at Kerem's apartments. They are very-well located near Galata tower at the heart of Istanbul, yet the apartments are on quiet street and I had a good sleep. Kerem was very helpful and we communicated flawlessly. Self-checkout instructions are clear and it is easy to get inside anytime of the day, which was really helpful because I arrived late evening. The flat is suited well for short term stay :) Highly recommended!