Mssarix's place was exactly what we were looking for. It looked just like in the pictures and it had all the necessities that we needed for one month stay.
The Wi-Fi speed was great which was really important to us since we do online work. The apartment is spacious, warm and cozy. The cheapest supermarket we could find is right next to the building, just few footsteps away. The metro station is quite close too, as well as the bus stop that could take you to the center of Kartal where you can leisurely stroll along the coast or rent a bike for a bit of exercise.
The apartment is quite far from the city center, though (1.5 hr ride) but if you wake up earlier, you can still see a lot.
We also had some trouble with the fridge which kept breaking down for some reason, but Mssarix and his wife were super quick to respond and engage in fixing it. All of our requests were fulfilled almost instantly and easily. The hosts even baked us a brownie cake which was sooo delicious! They were truly an example of traditional Turkish hospitality.
All in all, it was a great experience staying in this place, and I would definitely recommend it especially for longer stays.