I think it's wise to have both a GPS & paper maps. I predominantly use the GPS and save the maps as a back up and to preview the route before I travel.
One key advantage of the GPS is that regardless of where you are, if you ask it to find the nearest Hospital or Police Station, it will not only find it, but show you how to get there. Quickly. If medical issues are a concern, this is important.
Also, one time when returning home in a very thick fog, my GPS showed me I was approaching an intersection way before I came across the stop sign popping out of the fog. If there was a sign showing the intersection before that, I didn't see it. I wasn't travelling that fast, either. By setting the scale according to your travel speed, the GPS gives you a "heads up" as to twists, turns and intersections coming up in the road. I find this very helpful when driving at night in unfamiliar territory.
Lastly, and probably for what I use the GPS the most. When leaving the campground for a day excursion in the minivan I set the campground as "Home". Seems those brochures and internet web sites are great at telling you how to get to THEIR location, but not too good on getting you home. It gets even more confusing when taking in several sites during the day and returning at night. The GPS gets us back very nicely. Just one less stress in life.
And yes, you do have to use some common sense. To the person who said the GPS wanted him to turn onto a road which led him to a river in Connecticut... that's probably because seasonal/limited run ferries can be found here in the northeast. Again, in settings, tell it to avoid Ferries.
~Rick