I would say acquired taste but I dont remember not liking it at any point. Dr Pepper zero is also the closest you can get between zero calories and tasting the most like the original.
I watched the "British Kids try whatever" series and they described it as tasting like medicine. If thats what medicine tastes like over there I understand why their teeth are falling out.
Don't forget Americans drink everything cold so maybe that has something to do with it. That's our Turing test here, if someone claims to be American and hate cold drinks we open fire immediately.