The compass graphics can be shown in a pseudo 3D mode.
The GPS can be used in airplane mode or in places without coverage. It is recommended for outdoor use. Depending on different parameters, it can take a time to start to provide coordinates.
You can modify the texts of the Cardinal Directions to adapt them to other languages. It is only going to show the first letter.
The accuracy depends on your device. Normally it is better when device is used horizontally. If the accuracy of the magnetic sensor is not good enought, you can improve it by moving your phone a few times, drawing a figure of 8 in the air.
Magnets and metal parts can affect the performance. Do not use it near them.