IDEA's scala support still flags bogus errors (e.g. it doesn't seem to infer the type of a Kleisli { ... } correctly). It's one of the things keeping me on Eclipse.
Its scala refactoring is quite limited (even organize imports doesn't work, can't move a type out of a file without moving it to a different package which will sometimes fail anyway, no "generate interface implementations" or "move method to parent class"), autocomplete is painfully slow, and every so often the UI freezes for several seconds.
