Good reasons to be cautious, but a game changer if it works. This is gene silencing rather than gene editing so in principle risks to humans and the wider environment are relatively low.
The important thing for safety is that this works at the level of RNA rather than by modifying DNA (which is how things like CRISPR work). Actions at the RNA level are effectively reversible; once the interfering RNA degrades the effect will go away. On this basis you can predict that it's unlikely to have many deleterious long-term effects, although you should still do trials to check.