I found it to be most useful as a carbon supplement in non-CO2 injected tanks (low tech tanks). When dosed per instructions, it provided a noticeable benefit in plant health and growth. It is not anywhere nearly as beneficial as injecting CO2, but it is better than nothing. Additionally, it acts as an algaecide for certain types of algae.
When dosed daily, as per instructions, it may melt Anacharis (Egeria/Elodia), Vals, Duckweed and Marimo moss balls (which are a form of algae). These plants can be trained to use it if adapted slowly by not doing the recommended “initial” weekly dose and then just half-dosing every other day, gradually building up to recommended levels. Vals, for example, will initially melt and then re-grow fully acclimated to it.