Hey Jeremy, most likely what you heard about some guy, who is some sort of investor or fund manager, making claims about Herbalife being a pyramid scheme. While I am not making claims against this guy (whose name I will not publish), but in the past other people had made negative claims attacking other companies which were made in order to drop their stock prices so these people can buy stock shares cheaper, and then later re-sell at a profit once the scare if over and the stock goes back up to it's normal or pre-attack prices.
While I do not use Herbalife product as they are pretty low rated, the Company and the way they market/sell their products is a legitimate method of business called direct sales using independent sales people. This is the same business model as Avon, Mary Kay and other well known names. In fact, most of these products would be more expensive if the manufacturer used conventional routes for marketing such as national advertising, wholesale and retail distributors chains, and the requisite shipping and storage related costs.
While Herbalife products are not manufactured in a process that guarantees purity, potency or lack of toxins, they do offer a satisfaction or money back guarantee. I know people who take Herbalife products and I believe them to be as safe as any other food grade GMP manufactured product.
According to the Comparative Guide to Nutritional Supplements, 3rd edition, by Lyle MacWilliam, BSc, MSc, FP, the only Herbalife product among the daily multi-nutritionals listed that I could find rated that was rated, was Formula 2, which received a score of 14.8 out of a possible 100. Pretty low in anyone's book. But do your own research as there are a couple updates available to MacWilliam's Comparative Guide. Again, I think Herbalife products are likely safe, you could however do much better, but your original question if this is a scam is simple - no, Herbalife is not a scam or some pyramid scheme or anything of the sort other than a Nutritional supplement company using the direct sales - networking marketing business model.
Like I always say "Let the Buyer Beware". Good luck Jeremy and I am glad you are thinking of your children's health as well as your own. Children in today's world face more challenges that ever before with processed, high glycemic and GMO foods and the inherent lack of nutrients available in these foods, not to mention the highly toxic environment they are exposed to often on a daily basis.