It is a nice flat, but most other things are not. The worst thing about this apartment is soundproofing. While it is acceptable during the day, at night you will hear everything happening in the street (loud music, cars, people screaming, etc). There is also a mosque just around the corner, you will hear it too.
Building itself is ok, but premises don't look safe, I don't recommend walking there at night. Streets are narrow, dirty and Full of rubbish. While Taksim Square is in 8 minutes on foot, it is situated in the worst part of this location. I was misleaded by the apartment name, it is NOT on Taksim 11, it's on a narrow side street.
Cleanliness can be improved also. Jacuzzi dors not look to be clean. One of 3 air conditioning units didn't work. Our suite is on the top Floor and it gets very hot during a sunny day.
We have stayed only one night out of 4 we booked, because sleep quality in this apartment is one of the lowest I ever met. Apartment is very noisy at night and you should consider it if you decidem to book it.
Onur is very nice, through he doesn't speak English at all, this was not a problem for us.