We had a great stay at Damir's place, we were 4 over a long weekend. Everything went smooth, the apartment looks exactly as described in the pictures, there are 2 separate bedrooms with enough place for 4-5 people.
As for location it is right in the middle of Taksim, getting out of the house and you will be in the heart of all bars and restaurant, worth mentioning that the best kebab I've eaten @ Durumzade is 2 min away. If you expect a residential area, then you won't find it, however no need to worry about safety since a police station is right at the entrance.
The only negative remark is that at some point the electricity fell off for a couple of hours and there was no light in the apartment and stairways.
As for Istanbul, one of the greatest cities I've have ever seen.

I highly recommend Damir's place.