blind taste tests actually showed people preferred New Coke's taste! it was purely an emotional/brand loyalty backlash, not a taste issue.
flopped almost instantly after launching in 1985, backlash was so bad Coca-Cola brought back the original formula (as "Coke Classic") within like 3 months. business schools still use it as the textbook example of a market research disaster.
the whole thing might have partly been a genius accidental marketing move, sales of "classic" coke spiked afterward from all the nostalgia and outrage.