It tasted like Pepsi! A lot sweeter, with fewer 'dark' notes.
Pepsi did an advertising campaign back in the 70s, called The Pepsi Challenge. In malls and supermarkets, they set up tables were anyone could get two little cups of cola, one Pepsi, one Coke, but unlabeled. Then they were asked which they liked better. What they found was that about 75% of people who said they liked one or the other better were not able to tell the difference! Pepsi reported it in their ads as '75% of Coke Drinkers Liked Pepsi Better!'
This convinced Coke's management to change the traditional flavor of Coke to make it taste more like Pepsi. One of the biggest corporate mistakes in history!