This is just a tremendously beautiful apartment - to the extent that it was tough to leave! I wish I lived here. Decor is minimal, with lots of exposed brick and wood flooring. It's got a cozy little nook that goes above the street, and a balcony that offers a beautiful view of the city/Bosphorus. It's far enough from the tourist areas to feel a bit more laid back, but close enough to the main strips in Beyoglu that it's easy to go out for food/drinks/etc.
My only note would be that the windows in the bedroom seem to be only single glazed, and the street noise can be loud at night - Istanbul is always bustling, bring earplugs if you're a light sleeper. Highly recommended!