Ali was a brilliant host. He gave us a useful tour of the area around the apartment that gave us a great sense of the place. He also let us store our bags in his office after we had checked out, which was above and beyond what he needed to.
The area itself is perfect for anyone wanting to visit Istanbul: quiet and laid back, which is a welcome change after a day in the city centre or the markets.
No reason I can think of to rent anywhere else when you're in Istanbul.