Originally, Revels had orange creme, coconut, toffee, or peanut centres, along with Galaxy Counters (Minstrels minus the exterior shell) and Maltesers. However, the coconut centres were later replaced with coffee creme, and the peanuts with raisins. Making the revels sensation what it is today.
Mars Revels has become a well known brand and confectionery that is great for the old lucky dip, emphasized in the adverts by the depicted "tasting wars", coffee being the unwanted flavour. Their well placed catchphrase "which one will you get?" also continues this idea.
The Revels flavours have all been made to a similar size and shape to help the customer struggle to distinguish between them and hence pick a random flavour.
Some of the flavours are great, everyone likes the malteaser, caramel and chocolate, but others not so much, the orange (a nice idea but not done particularly well here) is very dry and sweet, almost too much for many people. Coffee is preferred by the older consumers but not the younger people.
Because of these problems revels isnt nearly as popular as other confectionary chocolates, but the idea, if worked on a bit more can still be very effective.