One of the best map/sat nav apps for my iPhone is the Apple Maps app itself, it is always upto date and very smooth in tracking my location. Although I do like Google maps the Apple version seems much smoother. However, just recently someone introduced me to WAZE, which is a free map app with the option to join up with friends. It also includes Safety Cameras and other road hazards free of charge. It has a very nice 3D display and auto changes colours during the hours of darkness. Give it a try.