From personal experience however, I will not be using Haskell again for a larger professional project, because our team ran into too many time consuming issues and problems that have been solved successfully in other languages/environments (especially the JVM) like dependency management or reasoning over runtime characteristics before deploying the application on production systems. Especially memory consumption is very hard to predict.
Of course, the language also has its benefits and even after some years it tickles your brain just the right way.
I like programming in Haskell very much, but in real world projects (you know - when you work in a team not only consisting of PhDs) I prefer Scala or Java, because getting a war file deployed or profiling an application is just so much easier.
YMMV, of course.