It is funny how different things are.
I'm with Mike, I live at the opposite end of the UK in Cornwall and do most of my reasonably local walking on Dartmoor. The las 2 trips I have done have involved walking on a bearing in 0 visability and could not have been contemplated without decent navigation skills!
I have a very basic GPS app on my phone which gives me a position if I really need it. I have only used this once, in January when I was out with my 11 year old daughter. Had I taken a wrong turn it would have involved an extra 10 miles or so which she wouldn't have coped with, so better safe than sorry. Had I been on my own I would not have bothered with it.
I used to have a garmin about 10 years ago when they first started to be affordable. It did not have maps on it just way points etc and I found my self using the map more than the GPS as I found a waypoint in the middle of a blank screen fairly meaningless. I think a modern GPS with decent mapping software on it would be another story, but electronics go wrong, so you would still need to carry a map and compass.
Using electronics also raises the issue of power, there just doesn't seem to be alichtweight option. When I first got my android phone I thought that might be the answer, you can get some very fancy mapping software for it, it is also a phone, a camera and can track where you are, a feature my wife really likes when I am off on my own! However the battery only lasts for 7 hours and unless it s mid winter, I walk more than that each day. I have tried carrying spare batteries, but at more than 1 a day, it soon mouns up. I tried a battery pack which you plug int with a USB. That gave me an extra 2 days, but then you have waterfroofing issues. I looked into solar chargers, but they were relatively heavy and we are not always bathed in sunshine!
My conclusion was that some knowledge and a map and compass was the best and lightest option.
I also use laminated maps which are a bit heavier, but dont fall apart at the first sign of moisure, and double up as an excellent picnic blanket when you stop for lunch!