Nothing's as good for exploring as a paper map. The screen on any GPS is just too small to get the big picture, or to be able to scroll around while maintaining reference to where you are.

Laptop, or paper map... which one fits better in your jersey pocket? The GPS is terrific for navigating pre-planned routes, locating yourself on a map, or bailing yourself out when you're really lost, but I wouldn't rely on it for exploring.