Map and compass still work, but I saw a guy get lost using map and compass because he took a bearing on the wrong peak; based on that he turned down the wrong valley. It can be difficult to navigate off terrain features when the terrain mostly looks the same.

I look at the GPS as a reality check. While it's true that anything with batteries, circuits, et al can suffer catastrophic shutdown, 99% of the time they work just fine within limits of their battery life -- carry spares. I've never had one of my Garmins fail for anything but battery life.

Turn the Geko on, let it find the satellites and plot its position. Are you between waypoints or have you drifted right or left? How far to the next waypoint on what course? Done, shut off teh GPS to conserve the batteries and continue to navigate using the compass. Best of both old and new.