Wikipedia informs me that Acerola should taste a little like cherry.
They taste like mild cherry. A little medicinal but not hardcore like Dr Pepper. It's certainly a flavour I've had before. Perhaps a little... powdery (?) to begin with but settles down.
I really like them.
In the Netherlands this year they released three new "Summer Edition" flavours: Mango, Tropical Acerola and Passionfruit. I can't see Passionfruit being the third flavour here (assuming there is one) as it came out last year. Passionfruit Mint appears to have bombed here too, it's not longer available. Good, it's rubbish.