Our stay at Saban's studio was just amazing. The apartment looked exactly like on the pictures and we had all the service described on the website. Both bedroom and bathroom were clean, we even had tea in the apartment and the huge balcony was used every morning to enjoy the sun, even in december.
The cleaning lady came every day which made our stay even more enjoyable since we didn't have to bother with that.
The location in Sultanahmet is really good when you want to visit the touristic yet cultural center of Istanbul. Sights like Aya Sofia and the Blue Mosque are appr. a 5-10 min walk away and the neighborhood is calm and peaceful at night. We moved to Beyoglu after 5 days in Sultanahmet since we wanted to experience another part of the city. So we would recommend that you stay in the old part of Istanbul for a few days to see all the amazing monuments and then go and see the more "local" part of the city.
Regarding Saban, we just met im once but he was very very reliable, always replied when we wrote to him and made the stay therefore to a great experience.