We were in Istanbul for 2 nights in April .. We were really impressed looking at the pictures of the place.. However, unfortunately did not do much research on the approach road. It is quite a bit of a walk from the closest bus stand, and the area is not the best to say the least. Since we were a bunch of all women travellers, it was specially not very comforting. Within the apartment building, however, the hosts have taken all the security precautions. I would still not recommend it to an all women group. None of the taxi drivers knew how to get there at all, one of the cab drivers even tried finding out by making few calls, but with not much success. It is however walking distance( without luggage) from Taksim square. So during the day walking to all the touristy places was fairly easy.
The hosts said they would be available if we needed some help, but unfortunately our timings did not match much. We tried contacting them on three occasions but on all occasions, we either did not get a response or got it too late. On the final day too,we had to leave the keys on his door because no one was available for checking out.
All in all, it is a nicely made apartment, but my major concern was the approach road to the area and the pain we had to go through to reach the apartment via cabs late at night.