Our stay at Sah Aparthotel was great - Necati was very accommodating and communicative, and even though we were delayed by Istanbul traffic on our arrival he ensured that our check-in was still very smooth.
The apartment was a spacious room with 3 beds (one double, two single), and the kitchen has all the basic cooking utensils. The location was amazing - we were a short walk from Hagia Sophia, the Blue Mosque (Sultan Ahmed Mosque), the Grand Bazaar, and we barely had to take transport during our stay. I would highly recommend staying here just for this.