The apartment itself is reasonably clean and comfy. Ceren is the best host, amazingly helpful with a good command of English that can come very handy!
The location although great on the map and close to Taksim area, is surrounded by very steep and one-way roads and many taxis refuse to drive to the door step. If you are not keen on climbing or are travelling with elderlies, you should keep that in mind. There was also a pile of rubbish a few meters from the apartment almost everyday, which I found was not uncommon in Istanbul, but made every walk to and from the place unpleasant.