Antonio's place is perfect. The building and the apartment are new and very clean. The apartment is located on one of the highest floors and the view from the balcony is breathtaking. The apartment is well-equipped, there is a dedicated study room that will come in handy if you need to do some work, and the kitchen has everything you need to cook fresh and healthy meals every day. It is also worth mentioning that the internet in the apartment is superb. There is also a spacious gym in the building that we enjoyed using. The communication was perfect. Each time we had a question or a request, we got a prompt, attentive, and helpful response. Communication with the hosts made us feel welcomed immediately.
The neighborhood is perfect. There is a weekend market on the same street the building is located where you can buy fresh groceries from local farmers. There are lots of smaller shops, restaurants, and beautiful narrow streets you can explore. And, if you are willing to walk for 25-30 minutes, there is a lovely Kanyon shopping mall with many stores, restaurants, and a cinema. It is also important to note that Kagithane isn't a touristy neighborhood, and we loved this a lot.
My wife and I highly recommend the apartment and the hosts. When we are in Istanbul the next time, we will stay at this apartment again :)