If you're visiting Palm Beach County, there's plenty of restaurants to choose from, but the Bavarian Colony is the only place I've found in this area (PBC) that serves up authentic German food.
I couldn't tell you the difference if it *wasn't* authentic, but my fiancé’s German and we used to go up there quite often when we were in the mood for some German food, but were too lazy to cook it. Now we're too lazy to drive up there so we cook at home. Go figure. LOL
The establishment is owned and operated by a German (Dieter), who's parents owned and operated a restaurant in Germany successfully for years -- they tell you the story on the menu.
The service is prompt and courteous, but be aware that the dishes are made by Dieter to order so take into consideration that you may be at the place longer than if you went to Olive Garden or something.
If you like German Black Forest cake, my fiance tells me that Dieter's comes close to how they make it in Germany (although still not as good as in Germany). You have to call ahead to see it Dieter made it -- if I remember correctly he only makes it on certain days. For all I know he doesn't make it anymore, though so definitely call ahead.