Been and seen two serious production apps in it. It's a mixed bag imo. People are very excited about the language features, but don't talk about the complexity. People talk about how great the JVM platform is, but don't talk about GC problems and excessive garbage generation in Scala. (eg: You can't use the map data structures without generating temporary tuples)

I think that for "programming in the large" that Scala is not going to be a winner here. I'm talking about a single code base with hundreds of engineers with a big eye towards maintainability. Because lets face it, for a 1 person small project, it doesn't matter what language you use as long as it provides single developer productivity. But once you talk about large team projects, things get very difficult. Scala only compounds this imo.