Actually it was a marketing success tho not in the intended way. After new Coke was release there was a fan backlash. An American icon had been messed with and changed and people hated it.

Before new Coke was released Pepsi and Coca Cola were virtually neck and neck. Coke always led but not by a whole lot. Then new Coke was launched. The American public went ape shit over it and 'classic' Coke was brought back. Since that happened Coke went head and shoulders ahead of Pepsi and Pepsi has never captured back that neck and neck race it once had. New Coke Succeeded by accident. It reminded the customer what an iconic image the original was made everyone embrace it like a long lost relative when it was returned. When you get right down to it, new Coke was the biggest success Coke has ever seen. Just not in the way it was intended.