If you can read a map, know how to use a compass, and your maps aren't too out of date, then you've certainly reduced the odds of getting lost. If that's your sole concern, then you have less need for GPS.

But a map isn't easy to use while you're riding, so you'll be stopping more often to use it. A map isn't backlit, either. A map may show you the approx location of the public library, but it won't show you the location of the nearest grocery store as well as its street address and phone. Of course, a map won't provide turn-by-turn navigation or give you the actual distance to your destination, an ETA, or elevation data (unless you're carrying topo maps, too).

What do you expect your Touch to do?