I must agree with feanaro: Haskell IS a playful and experimental language. Its unofficial motto is "avoid success at all costs", which should tell you something about the playfulness of its community.

As for what you learn from it... you say you didn't see any gains? I take this to mean in your previous languages you already programmed in a functional style, with purity, referential transparency and lazy-by-default evaluation? I find that hard to believe :)