I played this game a few months ago on a cruise. It seems to have most of the features of Spanish 21, but even more positives for the player. The big negative of course is that they remove the queens from the six decks (the tens are removed in Spanish 21). But in comparing the rules between Fun 21 and Spanish 21, Fun 21 seems to have more that favor the player. (This is not the same game as Super Fun 21.)
Does anyone know if there is a basic strategy layout for Fun 21? Or a counting strategy? Using a very rudimentary ad hoc counting strategy, I was able to make several thousand dollars in just four days with a betting unit of $5. My max bet was only $20. It could very well have been positive short-term variance, but I got the sense that if there was ever a beatable game, this was it.