We stayed for couple of nights at Ceylan's place. It was an excellent staging post for a flight out via Sabiha Gökçen airport, as the cheap airport buses (HavaBus) leave from the seafront bus station nearby.
Kadıköy is an enchanting part of Istanbul, excellent for cafés and restaurants and vintage clothes shops. Once we'd figured out how the ferries work, it was only our pleasure to sail across to Eminönü or Taksim (for a very few lira) to where the major tourist attractions are, then enjoy a romantic walk along the Kadıköy seafront in the evening, spotting cats. It's a stress-free and convenient way to explore Istanbul.
We enjoyed having access to a washing machine at the flat—along with a great balcony for drying clothes on—especially before our flight back. The bedroom was fine, but we preferred lying on the sofa bed in front of the smart TV. The kitchen seemed very well stocked, although I couldn't find a lighter for the gas stove anywhere. Check-in isn't automatic, so just remember that. All in all, the flat was very clean and cosy.
It was only a brief stay, so it's hard to write all that much, but—even so—we both felt we could have stayed for a month! So, then, I hope you won't hesitate to book your stay at Ceylan's property.