This is definitely worth adding to your excursion list. It's a must see if you're into alcohol, history, and how things are made. I just went today and my group had a fun time!
The tour was awesome! It lasted for about 30-45 min and they walked us through the rum making process. A few people on the tour got to press out sugar cane by hand and the whole group received a sample. We also got to taste fresh molasses! And of course we has LOTS of samples of different rum :D Let's just say all the tourists were walking out with big smiles! They also give you a free mini bottle of rum on the way out.
Small tip: Its true, the rural roads are a bit rough getting there, but the bumpy ride is worth it. Plus you get to see the beautiful scenery! Also if you are able to stop by some of the food vendors on the way out, you'll please your inner foodie by indulging on local food (fish fry, bammy, festival, pepper shrimp, and local fruit).