The unit seems to act exclusively as a rental, the host never lives there. The result is that it doesn't get quite enough love. When we stayed there the showerhead holder was broken, one of the curtains fell down when we tried to close it, the towels were noticeably old and WiFi was really unstable. The most annoying issue was certainly WiFi, as it was sometimes so bad that it was unusable. The WiFi access point was likely on another floor, I haven't seen it anywhere in the unit.
On the positive side the view from the little balcony is pretty awesome. That balcony is a nice place to have breakfast or just a cup of coffee.
The apartment is close to Taksim Square, which is both good and bad. The good part is that there's a lot of shopping and dining nearby and it's easy to get to various landmarks. The bad part is that the area is crowded. We've also observed some kind of a fight nearby and seen the police frisk a group of guys a few blocks away shortly after sunset. I'm not sure if that's enough to call the area "unsafe", but I would not walk there alone after dark.
You should also keep in mind that there's a giant mosque very close to the apartment and that the first call to prayer is around 4:50 AM. I personally think they sing beautifully, but if you can't easily fall asleep after being woken up at 4:50, you may want to stay at a different location.