This is probably the easiest hotel in the city to find. Pretty much every taxi driver in town will know where it is but if they don't, simply take a bus, yellow dolmus or taxi to Taksim Square and it will be there right next to the Ataturk Cultural Centre.
From the airport
Take the E5 motorway and exit at Beşiktaş onto Barbaros Boulevarde.
This trip will be around 30 minutes but allow more time for traffic jams.