Just great! The apartment for comfortable long-term living, not just a random bunch of rooms. No need to look further!
As described, as on photos. Spacious, bright, comfortable. Dedicated office room with big desk and a proper chair (now that is the "dedicated workspace" that AirBnB should check for!). Washer with a supply of detergent and a dryer. Combi heating in all rooms. A real kitchen with a safe gas stove, a dishwasher, microwave, lots of utensils, kitchenware, dishes, sauces of all kinds, big fridge, kettle, electronic water dispenser (bottles were supplied by the host on a short notice, thanks again!), not to count stuff found in closets (mixer, grill, probably something else). A big hall. A big bedroom with multiple drawers, nightstands and a big bed for two. A beautiful living room with a TV, AC (only in this room), aquarium, sofa, another bed for one, and a small balcony. Electric sockets and cables are available whenever you need them. Internet is stable.
The building is in the middle of a steep hill and location is not perfectly central, Taksim is about 20-30 minutes walking up and down multiple hills through somewhat shady areas. But taxi is cheap, and you can ask them to get you right to the entrance, there is an elevator as well. A good selection of markets is 5-10 minutes uphill. The cat room really exists, the cat is not really friendly, but it's independent and is ok with sitting in its room. The second peculiarity is a directly visible minaret (~170m), so you can hear adhan with windows open. Although I'm a light sleeper, I had no troubles at night once I closed the window in the bedroom.
Overall, highly recommend the apartment, Elefteria, and her son George who helped us a lot. We had a great time staying and working, all questions were answered promptly. Thanks again!