Selin's place is exactly as described except that it is bigger than the photos of indicate. We had two boisterous kids with us and when we were at one side of the apartment and the kids at the other, we couldn't hear them!
The apartment has a large, fully-equiped kitchen and effective aircon. The area is up-market Nisantasi and the apartment is at the centre of the area - close to shops and and parks.
It's a short walk to buses and metro if you want to use public transport (which we do - taxis in Istanbul are cheap but the traffic can be intense so it's often quicker and more relaxing to use PT)
We highly recommend this apartment