Worth a visit, the karst landscape is quite unique. The route is very complex, and surprisingly, there's no panoramic map, and the signage for attractions is minimal.
I don't think it's necessary to hire a guide at the entrance. Most guides, to save time, only take you along the main route, skipping all the side paths. You can actually explore on your own at your own pace; it's not complicated. The trick is to just follow the man-made paths, and you'll be fine.