I had an amazing stay at Reine's.
She was incredibly welcoming and gave me many local tips about Istanbul that made my visit much better. The flat is nice, quiet and warm, with a decent bed. There is an adorable well-trained and very friendly dog which is a huge plus as well :)
The location is perfect. Short walk to the port to grab a ferry to any main attractions: Sultanhamid, the Prince's island, Karakoy, or Besiktas. The area also has tons of nice quick breakfasts and coffee.
Direct transportation links to Sabiha airport, with metro and bus running in the very early morning and until late in the day, making it very convenient for early and late flights.
I would definitely recommend staying here!