I've tried Scala out for several shorter projects and have left unimpressed by its overall design. It has a great list of features, the type system and actors are my favorite, but it lacks coherence. Scala is usable and people build real software with it, I'm certain that what I dislike about the language is irrelevant to some.

I hoped for Scala to be Haskell on the JVM but it felt more like C++. It's clumsy, which may be the result of feature creep and lack of a single, strong design philosophy.