There are many overwhelmingly wonderful things that I enjoyed about my stay at Zeynep's place:
It is centrally located in Kadikoy and not too far of a walk from plenty of amazing restaurants, the ferry and bus station, the Moda waterfront, shopping, sights and attractions, and it captures the spirit and charm of eastern Istanbul away from the hustle and bustle of the more tourist-driven European side. Inside the apartment it is well maintained, small and accommodating for one to two guests and stylishly decorated. Zeynep was a gracious host, and even though she was out-of-town during my stay, she was immediately available whenever I had a question or a concern.
All that said, it is only fair I quickly glance over things that others may feel are deterrents during their stay: the location is on the top floor of an older apartment building, and although it was not difficult for me to climb the stairs with luggage in tow there is no elevator -- so if you are not able-bodied, this may not be the best place for you (however, bear in mind MANY buildings in Istanbul are older and do not have proper accommodation); the laundry machine rattles a bit violently and I worry it could cause damage to the gas pipe that is attached nearby; the apartment can get a bit stuffy during the summer-time so opening a window is often a necessity however the neighborhood is lively at night and may keep you awake with the noise.
Overlooking the minor downsides, I highly recommend staying at Zeynep's place if there is availability and if you are wanting to see the more quiet, local side of life of Istanbul. There are many things to do nearby this rental that you should never be out of options for things to do. Enjoy your stay.