Erdem's place was great. It was our first time in Istanbul, and we had no idea which neighborhood to stay in, and we were glad we chose this one. Taksim Square had Times Square vibes with the liveliness of the area, and the nearby metro made it easy to get to the old city.
The apartment itself had amazing views, and it was nice with plenty of room for four people. The shower was like a human car wash (in a good way). The only negatives were that the bedroom shades didn't keep much light out and the bedrooms got a little hot even with air conditioning in one of them (there were also fans that worked well, though).