The reviews here seem pretty accurate. The place looks very much like the photos, and Berk and his family are tremendously responsive.
Our family group struggled a bit with the hills, so I would say this home is probably best for young groups willing to walk and explore the plentiful nearby sites including the shopping and restaurants around Istiklal, and the shores and cafes of Karakoy.
I will try to highlight aspects others haven't mentioned:
-The living room was quite a comfortable room to hangout with family. Bright, and spacious and with appropriate couches and tables.
-The third bedroom was a bit claustrophobic. It is a small room situated with no windows, under a staircase, meaning limited ceiling space. It was quite manageable for our group, but I could see it being an issue for others.
-The kitchen was properly stocked, and clean. There was cookware and the refrigerator was in good condition.
-The garden had only limited greenery. Perhaps it was due to the time of year, but the garden was basically a dirt patch.
-The location is quite central, but the accessibility was difficult. The issue is that the hills are considerable, almost San Francisco-esque. The alternative of taking taxis did not prove simple, as they seem to refuse to enter the neighborhood about 33% of the time, due to the challenging, narrow streets. (The track record of Uber was much better, probably a 10% refusal rate.)
-There are lots of small neighborhood grocers nearby. It was quite easy to get bread or water on short notice, even at late hours. More comprehensive shopping options, like Carrefour supermarkets, are just a bit further away, about 20 min walk or 5-10 min by Uber.
Overall it was quite a pleasant stay.