I think the package ecosystem is a big barrier. I code on OS X, and it seems like half the Haskell packages I try to install fail to compile. I always get super motivated to do my next project in Haskell, but then give up when I can't install the required libraries. Maybe the situation is better on Linux.
In any case, I think Haskell will need reliable package management on at least OS X and Linux before most developers consider it a serious choice for real projects.
In any case, I think Haskell will need reliable package management on at least OS X and Linux before most developers consider it a serious choice for real projects.