That may be true — it may be the only Haskell program that people regularly use — but I'm not sure how that counts against Haskell. I'm no fan of Haskell (I used to be a huge pure functional programming fan, but over time the shine has worn off and I've realized it's just another dogmatic paradigm) but having even one widely used and liked tool is actually exemplary for a highly idiosyncratic non-mainstream language like Haskell, to be honest. I think it's doing pretty well for itself.

I didn't say it was a bad thing, just pointing out that Haskell is not a terribly popular language and as such most of the apps that I've seen written in it are only used by Haskell enthusiasts (Darcs comes to mind).

I'm kind of a functional programming fanatic, evidently.