The Haskell community could silence the critics quickly by pointing to some real world open source applications which prove the practical usability of Haskell. So far there aren't much. Most of them deal with DSL. There are only two Haskell IDEs written in Haskell: Leksah and Yi. The only good native IDE (AFAIK) is EclipseFP, and that is written in Java.

Perhaps some Haskellers should take the effort and develop a really sophisticated Haskell IDE which Haskell beginners could follow and use to learn and advance in Haskell. Theoretic knowledge about Haskell is good but practical application is another thing.