Customers frequently report that Harpic 100% Limescale Remover is highly effective at removing limescale, including tough and built-up deposits, often resulting in a sparkling clean toilet. Many reviewers recommend the product and consider it to be among the best available, particularly in hard water areas. Its ease of use and ability to clean with minimal effort are often highlighted. The product's thick consistency, which clings well to the toilet bowl, and effective spout design are also noted. While many find the scent pleasant and fresh, a minority express dissatisfaction with it. For optimal results, several users suggest leaving the product to soak for extended periods, including overnight. Some customers also appreciate its ability to remove stains, disinfect, and act quickly. There are a few mentions of a preference for the 'black Harpic' variant, and a small number of users found the product less effective than expected or expressed doubt about its long-term cleaning action. Reviewers generally consider it good value for money.