There was a time when Rin bar used to be the most perfect detergent bar, but since then many detergent bars came and went away, although Rin is still there because many people still consider it the best one!
But nowadays, many really good and effective detergent bars like Ariel, Tide, Ghadi etc are available in the market, which does not dissolve too much like Rin and make less water consumption than Rin and produce better results!