Love everything about this place. I feel I received great value for the price and would absolutely stay there again upon returning to Istanbul:

-The Host: Fatih is a great guy. He answered all our questions, provided restaurant recs, and had the apartment stocked with useful items - hairdryer, city maps / guides, an umbrella, etc. He also responded to emails very quickly.
-The Area: You'll spend most of your days in Sultanahmet, but it's pretty touristy. At night, Galata / Beyoğlu (just walk up the hill towards Istiklal) are where I wanted to be. We went to some wonderful cafes and a couple of live music venues. It's a nice mix of tourists and residents as well, so you get to see a different side of the city.
-The Apartment: It was exactly what I expected from the pictures. It's a decent sized studio with plenty of room for two people. The shower always had hot water (really, that's all I need) and a kitchenette, though we didn't make use of it.
-Transportation: We walked down the hill each day to the Karaköy stop and took the tram straight across the water. It's three Turkish lira and easy to navigate. You're one stop away from the spice market, four stops away from the Blue Mosque / Ayasofya, etc.
-ENJOY!