Limescale Eliminator any good?

Normally these types of products fall into the category of snake oil, or nonsense with stilts on, pure pseudo science quackery sold by charlatans to the hopelessly misinformed.

I don't know about the product pictured - but it looks like the usual plastic box with wires that don't work, as they do not soften water (remove limescale) and it is highly unlikely gizmos like these produce any results to avoid scale sticking to pipes as they have no real before and after proof of conformance to scale reduction on any national or international recognised testing standards.

Usually, you would be better strapping a carrot on to your pipework instead.