Just to mention, I have seen a plugin for programming in Haskell in Intellij Idea; I didn't experiment much with the plugin but Intellij Idea is a good IDE.
Intellij IDEA is a great IDE. Its Vim bindings plugin is not entirely stable though, or wasn't when I last used IDEA. AS far as large java IDEs go IntelliJ is awesome. If their haskell mode is as good as their other language toolings then it is probably pretty good.