When I'm out on the road inspecting houses, I live by my GPS unit.
That being said, I'm on my second Garmin. The first one was flawless, but just got outdated and it cost as much to update it as a new unit.
My second Garmin has had some problems, although I suspect it's the area as much as the unit. GPS doesn't work well in Nebraska City, NE, nor in northwest Missouri.
But, Nebraska City is a screwed up town anyway, and I never did figure out northwest Missouri. I finally quit working that area 'cause I could never find anything. I'd be driving along, the GPS would say "Turn right on Road 368", and I'd look up at the road sign and it would say, "Road 426".
I was once looking for a food pantry less than 3 miles from downtown Savannah, MO, and neither GPS would find it. I finally just stumbled onto it.
The thing is, you still have to have a good idea of where you're going, GPS is just a good guide.