We stayed 5 nights at Hande and Emre's house and had a very nice time. Their apartment looks like a Vogue photoshooting set, the pictures aren't lying!
Kadıköy isn't in the touristic center of İstanbul, so you will have to take the ferry in the morning to visit the main tourist attractions. We loved the morning ritual of eating breakfast and drinking çay (tea) while admiring the surroundings. The location shouldn't discourage you from choosing their place!
Since it is located in a lively (and really cool) neighborhood, it can be loud during weekend evenings. Nevertheless, this didn't keep us from sleeping!
The room and bed are cozy and comfortable and we felt at home during our stay. Hande is a very kind and generous person. She took her time to help us organize the rest of our journey in Turkey, gave us tips on where to eat and what to visit. Plus, it was very pleasant to talk together!
Thus, we recommend staying at Hande and Emre's place. If we loved İstanbul, it's also thanks to them!