(Visited on a Monday @ 1pm) you walk in the entrance and it's m&m merchandise being sold to you. Next is a short hallway with large windows where you can see a few people moving chocolate through machines. At the end of said hallway, you get to try samples. Final part is one more gift shop area to see if you want to buy more chocolate. That's all.
If you're within 30 minutes of this place, sure, pass by. If you're further away, I'm not sure it's worth the drive + Vegas traffic for a 10 minute walk through and a chocolate store. My child was moderately entertained and then abruptly disappointed at the end. 3 stars for the delicious chocolate.