Still, I'd drive a car to the ferry dock, especially in summer. The highest point of the island is occupied by a WWII cement army bunker, the very last place that German soldiers occupied of Holland in 1945. Even so, it's very easy to see the whole island in one day because it is so small. There is a giant whale jaw-turned monument to be seen in the center of the main village. And just in case you missed it, there is also the giant whale jaw facsimile-turned monument to seen as well about ten minutes outside the village.
Houses have an architectural vernacular peculiar to the island.
Brick, asymmetrical, unusual, and pretty. Not many people outside of Holland except for a handful of Germans seem to make it to Schiermonnikoog. I think it's really unique in that respect. But if you're already in the north, or in the mood for something slower and off the beaten path, it's worth a visit.