Great place! Things I want to mention in particular:
1) It's big enough for 4 people. There's a common area where you can eat and just hang out, the kitchen has basic stuff to cook (stove, microwave, pans, kettle, etc.), we made our breakfast easily. It has three beds (two in one bedroom and one in another) and the fourth person can sleep on the couch in the living room.
2) The location is really good. Tram station nearby, supermarket, several cafes (where we could find smth to eat even during lockdown and Ramadan). Not even mentioning Blue Mosque, Aya Sofia and Topkapi in a walking distance
3) The hosts are the best! As it was mentioned in other reviews, this appartment is a part of a hostel. It's on the first floor and absolutely private, the hostel rooms are on the second floor, and there's always someone on reception 24/7. They sent us very detailed instructions on how to get from the airport and into the apartment, helped us with HES-code activation and printing out some stuff, recommended a wonderful hammam and made resevation for us, not to mention providing us with coffee every morning. Thank you so much, guys, you are awesome!