I give this place 4/5 stars based entirely on expectations I had in the cheap price.
The apartment is only a small walk to the popular tourist high street in Istanbul. Google maps made it very easy to find coming from the airport bus in Taksim square. You don't need a taxi if you have data on your phone.
The apartment is what I expected for the money: basic but comfortable. It was quiet and the beds were comfortable.
Downsides: the WiFi can be very slow when everyone is using it, and I had to ask the owner for the password as I couldn't find it in any information they sent over. However, they replied right away. Also the kitchen was unclean as the pots and pans were mouldy.
But the price is very cheap so for two backpackers it's all totally fine.
Thanks!