I strongly recommend Kürsads appartement ! It was very relaxing to stay in this hot spotted beautiful location in a blind alley just 1 min close to Istiklal caddesi. The appartement itself is very lovely designed with wooden floor and funitures who spend an excellent atmosphere! Also the bed is very comfortable to get the rest you need while travelling.
All in all i can sum up you would really miss a great accomodation if you wouldnt book this one!
Wishing you a great time in Istanbul,
Sophia