Phone mounts come in all shapes and sizes some are effective and some are not be it long or short term and I have gone through some amount of these over the years with them mostly giving in after a few weeks, In particular those that stick to your window via suction cup and what gives on these is usually the grip that holds the device.
This new one we got in from Mobile Fun is a good one in more ways than one. Its small and can be placed anywhere in the vehicle and has really strong magnets. I have tried several of these types before and the magnet is very strong compared to ones of old and you get two different sizes of magnets in the box. With the Ringke Car mount holder you have 360 degree access to your device and this is also ideal for larger phones too which is now the trend. If you want a small no obtrusive strong magnetic mount this is the one to get.