it seemed like the staff were very strict and not very trusting with guests, when I checked out they asked me to wait till someone check the room (perhaps they had bad experiences with guests nicking items from the rooms), I didn't mind waiting, but it was the first time I was ever asked to wait before check out till someone checks the room.
also, at some point I was locked out my room, had to go down check with the receptionist and she's given me a new key card, yet it didn't work either, so they sent w technician who have realised the batteries of the locks needed replacement and replaced them.
the room had a balcony, but the door to it was locked, and when I asked for the key to the balcony they said they don't have a key for it, which came across as strange.
apart from that, the room was really nice, and it was actually quite bigger than advertised, it was generally clean and comfy, and the hotel is perfectly located in a quiet area yet is a few minutes walk from Sisli centre and the underground/subway/metro stations.