We rate this place as 10/10. Our stay was comfortable and memorable. The apartment was much better and bigger than we expected and the location is perfect to explore many areas by foot - Karakoy, Taksim, Cihangir and many more. So many good cafes and eateries within 10-15 mins walk. We partied at Taksim area and slowly walked back home late at night without any issues. But be mindful that Beyoglu is very hilly and full of steep slopes and steps. Not for people with mobility issues.
The host, Jan, patiently answered all my queries and offered suggestions. Basic necessities are provided similar to full service hotels. There are two bathrooms and one comes with WC. There is also a huge backyard. The convenient store next door is open past midnight and has everything you need. Very good location, amenities and value for money. Highly recommended!