One of the reasons I like using a GPS with a paper map, and have a somewhat lesser focus on using a magnetic compass, is that in many midwest forested and wetland areas it becomes almost impossible to walk a straight line compass bearing (or is that an azimuth?). I fully suspect that the same thing happens in not-so-flat terrain.

I've read about and tried to use the classic methods for overcoming such issues, but struggled. A GPS with a built-in compass has the ability (somewhat miraculous to me) to continually point to my desired destination - and provide a distance to the destination - from anyplace on Earth.

I know that there is some level of GPS inaccuracy and there is the ongoing reality that the GPS could simply fail to function, but to me the capabilities are amazing. Still, it would be foolish to not bring a compass and not know how to use it with the paper map. If nothing else the compass allows me to turn off the GPS (save battery power) and still head in the prescribed direction.

I can imagine a day when a smartphone can be made rugged and waterproof enough that it will truly replace a GPS - even for use where cell service is not available. It's probably not that far off.