In one word: Fantastic.
Host: Cagdas is everything that you'd expect from a perfect host. He is warm, welcoming, on-time and fun to chat with. He walked me through every corner of his apartment in detail and was very responsive every time I contacted him during my stay.
Neighborhood: One of the cleanest and safest areas that I've seen in Istanbul. No problem walking alone on the street at 4am in the night. Apartment building is situated on a cute street which is quiet, clean and well maintained.
Location: It is a central and convenient location for getting to most places, Taksim, Levent, Besiktas, Maslak, the old town etc. You get the idea.
- 1-2 min walk: Local shops, grocery stores, restaurants etc.
- 5-7 min walk: Bus stops
- 8-10 min walk: Metro station
Also it takes less than a minute to find a cab on the street. Street parking is a bit difficult to find, but there's a reasonably priced parking lot across from the building.
Tip: If you will take a cab, just walk for 3 mins to Abide-i Hurriyet Street or Buyukdere Caddesi to avoid the occasional traffic on side streets.
Apartment: No surprises, same as in the pictures. It is neat and clean and feels spacious. Especially the master bedroom is quite large even with the king size bed. Lots of closet space in both of the bedrooms. Kitchen is a bit tiny but has all the tools and equipment that you'll need. I cooked most of the time during my stay. Bathroom has good size, water pressure and temperature controls work great. Living room is comfy, has a nice TV with cable connection, and also there's an HDMI cable if you want to connect your laptop to the TV (perfect for Netflix, yes you can connect now in Turkey).
Overall: I highly recommend Cagdas' place. Next time that I visit Istanbul, I know where to stay.