Great location, close not only to Hagia Sophia but also to the Marmara sea promenade on one side and boat station near Galata Bridge on the other. Very responsive host who helped us with booking taxis and other small questions we had, day or night. Pretty stylish space, well equipped kitchen. Very comfy beds!
Based on our experience with a small child, would not recommend the place for a family with kids - the apartment is very small, more like a studio, so noise will be a problem unless everyone goes to bed at the same time. Besides, the separate bedroom doesn't have a window but has a glass section of a wall, so light will be a problem as well. It's a nice place for a couple or, possibly, close friends if two bedrooms are required. The only obvious problem is the bathroom which is tiny, very basic and needs some serious fixing (the mixing tap is a nightmare, toilet seat is half broken, shower cubicle sliding doors are getting detached and could fall off, glass holder came off the wall, etc). Also, the price we paid for a week (€400 plus fees) seemed way too high but that's something we realised later and that's, of course, our responsibility.