We enjoyed staying at Kürşad's place - #6 Kumbaracı Suites - very much.
The place was clean, comfortable, with pleasant, simple decor. Although there was no kitchen (as was made clear in the details) there was a fridge and a kettle and some minimal cutlery, so we were able to eat breakfast there. There is a small, attractive balcony with a table and two chairs, great for those who don't suffer from vertigo.
The shower was good, plenty of hot water and no leaks, and the bed was very comfortable.
The building had a washing machine and dryer in the basement and washing powder was provided, all at no extra charge. That was very useful since we were travelling light.
There is a school next door so we could hear children playing during the daytime, but most of the time we were out in Istanbul then. At night-time it was very quiet.
The location is ideal. The apartment is very close to Istiklal Caddesi, which is the centre of activity in Istanbul with hundreds of restaurants and shops and several nearby access points to Istanbul's superb public transport system. Istiklal Caddesi is bustling and noisy all day and late into the night, but the apartment is just far enough away that we were not disturbed at all.
There is no lift, but if you are visiting Istanbul you should be prepared to walk up and down the hills which give the city much of its charm. A couple of flights of well-lit stairs are no problem.
Kürşad was there to meet us when we arrived and was available whenever we needed anything. We noticed that one internal door was sticking a bit and were planning to mention it when we left since it didn't cause us any real inconvenience. But Kürşad had it fixed while we were there, before we even mentioned it.
Overall an excellent place, ideal location and good service. Highly recommended.