I actually think this is a very poor answer.
This project is in its infancy and thus very easy to dismiss as vaporware, or if you actually used it you might come away with a bad impression (as you might with any alpha software).
The question itself is ridiculous and should prompt some socratic questions (what do you think Haskell is designed for?). Like most programming languages, it is not designed for any particular domain, just for high-level programming, and it can excel at most domains once good libraries are created.
I'm not saying it's a valid complaint; however, I don't think it's uncommon. I think the person in question was assuming that Haskell was designed for mathy/programming languagey type stuff (I'm being vague and mangling English because I'm tired :)).
This is a great counter-example: it's a project in a different field and, most importantly, the programmer enjoyed using Haskell for it. As long as it at least mostly works, the actual quality and polish of the project is immaterial--you cannot really expect a spare-time project, even in a perfect language, to be perfect; its existence alone signals that Haskell is a viable multipurpose language that isn't just a silly academic curiosity.
I strongly disagree that unpolished programs (done under time constraints or otherwise) signal that a language is more than something satisfying (academic) curiosity.
I am a contributor to the Yesod web framework (so I know this example is a good one - there are certainly others). Yesod is robust software used in production right now. Feel free to point people to www.yesodweb.com as an example. We are doing traditional IO-heavy database oriented web development, but leveraging Haskell to make things better in ways not possible in other langauges.
