It is a cozy appartament on the 4th floor (no elevator) with a nice terrace and a good view. Galata tower is right around the corner. Metro and ferry stations are 10-15 minutes by step. It is 30-40 minutes walk to Aya Sofia, Islamic Arts Museum and Dolmabahce Palace.The owner is really hospitable and attentive to details, he also allowed us to check in earlier for very acceptable price.
P.S. There is 18 minutes walk to a good place to have a breakfast, it is called Dogaciyiz.