Sat-navs are ace.
And, like any piece of lowest-bidder technology, not to be relied on exclusively. They're best used as a handy aide-mémoire after already working out the route on a map. I've got an atlas of Britain and an A-Z of London in my car, for when the sat-nav inevitably goes tits-up.
( flake has nothing against your right leg, Tue 5 Jul 2011, 0:10, 2 replies)

He's not wrong
I've got a satnav for work, but when work involves driving a 44 tonne HGV, you take the instructions with a pinch of salt. If the destination is really rural or you can see a railway line across the route, it's good idea to ring them. There's an industrial estate in Kent where if you're over 13' high you need an escort in and out, and if you get the custard powder factory at Knighton (Streetview ST20 OQJ) it's best just to stick a cork up your arse and kiss your loved ones goodbye.
(all my scars face forward possesses 2.5% of a hyperalloy combat chassis, Tue 5 Jul 2011, 9:33, closed)

My gran used to have the OS co-ordinates of her house written on the pad next to the phone (house was very rural) so if there were any problems we could give them to the emergency services they would know exactly where you are.

Fast forwaqrd to now, ambulances still get lost in that area and have to ask at farms for directions to houses / other farms where they need to be after the sat-nav lets them down
(liquidkristal, Tue 5 Jul 2011, 20:14, closed)