My mobile is my TomTom so I do need it in plain sight in my carwindow. and I need it to stay in place quite sturdy, so I can enter my next destination. So two things do count for me in a universal phone holder (which is by the way half the price of an original samsung one):
The suction and the fixation.
If the succer doesn't work in between minor temperature changes the cradle will fall off. And if the fixation of the arm does not keep it in place you will simply push the unit off or have your mobile dodge your inputs by waggling around.
This doesn't happpen here so 4 stars. Why not 5? because if your usb port on the bottom of your phone is not dead center, you won't be able to plug it in whilste the mobile is in the cradle.