It's very quiet apartment in 15 min to Taksim square close to 5-stars hotels. It's located on quiet street.
In 5-10 min you can find buses to the Eminonu, in 10-15 min metro and funicular to Kabatas.
Be ready to go up to the 3rd floor without elevator. The streets around the house are very hilly.
Pluses of the apartment:
1) There is very nice bed with perfect mattress;
2) There are a lot of spices and oil on the kitchen;
3) You can regulate the temperature of radiators, so there is a good air in the flat;
4) Owner is very friendly. They brought the second key complect and stayed in touch all the time;
5) The price was cheap (especially for this place).
Disadvantages of the apartment:
1) The sofa (the second sleeping area) was not very good. If you will use it, be ready to wake up with backache;
2) There was a faint sewer smell in the apartment;
3) There isn't microwave owen and the kitchen utensils are rather poor.
So, I think it's an excellent variant, if you need only one bed.