There's nothing wrong with that plan. Even in a nuclear war, those GPS satellites are still going to be up there in orbit sending timing signals from their on-board atomic clocks. The military designed them that way for a reason.

But as with any electronic device, make sure you have a backup plan if things go horribly wrong. A cheaper compass and the knowledge to properly use it are appropriate. If you have those as your backup, I don't think anyone will disagree with the idea. <img src="images/graemlins/cool.gif" alt="" />