I have Navionics loaded on mine, but its really just a toy, not a primary method of navigation. Works well enough, position agrees with my Garmin on board kit to about 5 meters. (Dont know if the anomaly is caused by the tablet or the charts)
Difficult to see in bright sunlight and very little water resistance (Dont ask how I know ). Fantastic bit of kit all round but better for plotting courses on the sofa than at sea.