> A success story by what definition? I cannot judge Haskell as I don't know it well enough.

In the sense that it looks coherent and incorporates a lot of lessons learned over the decades of functional programming.

Design by committee usually fails either by being boring or by becoming a Frankenstein monster made of various contradictory opinions of committee members. Neither is the case with Haskell.

And the only bad design decision that I know of, namely to not make Monad derived from Applicative, was corrected in a future release.