I use GPSs regularly. I wouldn't leave home without one. At the moment, I'm driving a Class D expedited delivery truck for FedEx Custom Critical. When I get a dispatch for a pickup and delivery all I have is addresses for two locations that can be cross country from each other. The directions and instructions I get from my dispatcher about how to get from point A to B are sketchy at best. No pun intended, I'd be lost without a GPS.
The big drawback for me is none of the GPS truly take commercial vehicles into consideration. The GPS in my truck du jour is a Garmin Nuvi. It. like all of its predecessors, is always directing me down streets that are restricted to vehicles sized like mine. A few times its told me to go under bridges that are not as high as my truck. So of course, I absolutely do not rely 100% on the GPS directions.
Whatever GPS system you are using or considering, they are tools. IMO, they are tools to be used in conjunction with other tools to help you plan a route. As long as its telling me an interstate or a state route I'll believe it. Once it says anything street or road I start calling for additional directions. I have lots of maps, rulers and magnifying tools in my truck. I also have multiple cell phones to use when the dreaded faded signal happens while talking to the one person at the plant who can articulate which streets around the location are part of the truck route.
To find the road less traveled, GPS are dubious. If no one is using the road you almost have to be on it for it to register on my system. If I put in an obscure road from several states away, the GPS can't locate it. When I'm near the destination it will do a screen jitter and find where I want to go.
For camping and traveling, I'd pretty much use a GPS like I do when I'm working, with caution.