Ata appartement is really a great place to stay in Istanbul for few days ! Ata is so kind and helpful you just can't have a bad time there :)
The location is perfect ( near bus and ferry station) you can take shuttle for or from Istanbul and Sabiha Gorçem airport very easily. In addition the whole Kadikoy Moda neigbourhood is incredible, you will find many cute restaurants and bars with excellent music ! We spent new year's eve there and it was one of our best new year celebration !