My sister came to pick us up from the airport and had a GPS device.
It was terrible. Every so often, anything from 20 seconds to two minutes, the thing would interrupt us, without a "by your leave" or even a simple "excuse me" to tell us something like "at the next junction go straight on". I mean , we can read the signposts, and we can tell the difference between a road gong into a tree-lined neighbourhood, and a road leading to the M1.
What would be a good idea would be a GPS that knows when to shut up, and holds its peace until it has to say something like "Sorry to interrupt, but that left turn you just made was a bad idea, go find a place to turn around and get on the correct route" or even better, though it would have to be a female voice (they all are in any case aren't they?) saying "now would be a good time to stick your head out of the tin box and ask for directions, don't you think?". Apart from that I've got no use for GPS's