This has a museum, hands-on classes at the Chocolate Lab, and a cafe, where you can buy a sampler to taste chocolate from different countries.
I've run into the same connundrum as Robert. We'll spend much of the day in Hersheypark, and have already spent money on park admission and/or concert tickets. We'll visit Chocolate World on our way out, and it's just not worth it to spend more money for their add-on attractions. Not only that, but we're typically pretty tired after a day walking around Hersheypark (rather hilly on the east side of the park), so we don't feel like doing the other Chocolate World attractions, especially since they cost more money. We're pretty happy soaking in the air conditioned dark ride, grabbing a freebie on the way off the ride, and walking around the store before driving home (nearly 3 hours for us).
You did miss out on the Trolley and the Museum portions. The trolley guides are Tokyo Disneyland quality and the museum was pretty interesting. It can't keep up with the speed of the amusement park, but Chocolate World is a great time.