It's location is odd, unless you have business in that area. i've passed the place (it's impressive) but wouldn't dream of staying there.

If you are wed to the notion of a Hilton on the Asian side, better to stay on the airport shuttle until the Kadikoy terminal and stay at the Doubletree Moda. Yenisahra is the Kozyatagi stop.

The Doubletree has a lounge, lovely views over water and to the European side, and it's an easy walk to the ferries.