This apartment is perfect for a large group of travelers, it is very spacious and kind of a maze at first. It has enough bedrooms with sufficient privacy for the entire group. The apartment is clean with almost all the amenities I could possibly we can think of plus a piano. The wifi was spotty sometimes but there are bunch of different hotspots that you can connect. Also, Manzara has an office right across the apartment so if you need anything the staff is super helpful. They've accommodated our early check-in and airport shuttle pick up. If you are a light sleeper then it might be problem because the streets and the building itself can be noisy until late hours, but that's part of staying in Istanbul (the host provides ear plugs). The kitchen is clean and has most of the equipment for making simple meals.
The apartment is in the heart of European Istanbul and close to many historical sites with easy access to subway and trams to both Halic and Asian side. Plenty of options to eat and shop on the street but you can easily take taxi or public transportation to Cevahir or Istinye park as well.
Highly recommended apartment especially when staying with a large group!