Great apartment in a great location. The apartment really is historical with super high ceilings, brick walls and original hardwood floors. The space was nicely modernized and simply decorated. The space is big enough and is quite clean and comfortable. It feels like home. The building has a modern elevator. The building is located in a quiet little street parallel to Istiklal Street (a main tourist attraction). The street itself is super safe with 2 convenience stores, a bakery, a store that sells fruits and veggies, all open until late at night. You will also find kids riding their bicycles and playing: a typical Turkish experience. Around the corner, you must try the bakery that sells Turkish borek and croissant-like pastries. The apartment is a short walk (like 5 mins) from the Rixos Pera (for reference): from there, you can easily reach the middle of Istiklal Street, Galata and the Pera area, all super interesting! There's a superb view on your way there, overlooking the Golden Horn (if I am not mistaken). The apartment is also well connected in terms of public transport: 2 nearby bus stops - Omer Hayyam or Tarlabasi - with many buses stopping by and connecting you to most of Istanbul. If you prefer the metro, you can take a walk or one of the buses for a couple of minutes to either to Taksim or to Sishane and take the metro from there).
Finally, Taner and Nicola are both great and friendly hosts! You will run into them in the building as there is always one of them available on site. Communication with them is great and they are always available to solve any issues that may arise (happened twice with me).
I definitely recommend staying in this apartment: it has great value for money and gives you a taste of authentic Turkish experience while being in the middle of the action.