Exactly, the Maginot Line worked perfectly at not letting the enemy through. Too bad the sneaky Germans knew how to drive through an impenetrable forest though...
Had the French continued the Maginot Line to the coast WWII would've looked like WWI, just with less dashing aeroplanes. But for some reason the Belgians and Dutch didn't like the idea of their lands being left behind. Nor did they allow building the line through their lands, so not to provoke the Germans.