We stayed for 3 nights in Maha & Chiko´s flat. The location is excellent, it takes less than a minute to get to Galata tower, but the best thing is that the flat is situated in a very quiet street. So you have cafes, bars, restaurants, and shops nearby, but then you can relax in the flat.
The flat has everything necessary for your stay, it's not very big but it's perfect for two people. It also has a mini-kitchen and air-conditioning which in August was great to have. It also has a nice balcony and a rooftop with a nice view.
Definitely an excellent choice of accommodation and the best area to stay in Istanbul.