Kerem and Nicad have been wonderful hosts. Very helpful and attentive, and do more than expected to let you feel at home. I've stayed here for the last two weeks and enjoyed every moment.
The room itself is the only one located in the floor, which means it is very quiet. It has a private balcony looking on the street. The place is very clean and convenient.
The building itself is nice and located right next to Taksim, but far enough to not feeling the noise. Its very quiet. The area is excellent when it comes to public transportation as well, very close to a metro station and to the funicular.
The neighborhood is far better than the Sultanahmet area, since it had much more authentic feeling to it, and it's much more local. You'd eat and party here better and cheaper...
If you look for an amazing Istanbul experience, take this one.