I'm not sure if it's accurate to say that the community is on the FP side, or if there's just an extremely vocal FP community within scala drowning out all the other scala community members.

A few years ago, this was very much true. The Dispatch lib for doing HTTP requests was particularly guilty of this - you had to learn a whole new mapping of symbols to methods!

I feel Scala is beginning to stabilize now. The recent release of 2.11 fixed several annoying issues, notably thread-safe reflection. The community is beginning to build some substantial and usable libraries. There's a still a long road ahead, though.

That being said, I doubt (and fervently hope against!) Scala will ever become Java++. Scala seems to constantly push the boundaries of language design. This is great, as it results in exposure for some lesser-known concepts into the mainstream developer community (e.g. Scala implicits ~= Ruby refinements).

With regards to language stability - the docs will specifically warn you against highly experimental features (e.g. macros), and for many you even need to explicitly import something to enable them.

The type system is very much rock-solid. Scala doesn't force you to use co/contra-variance or higher-kinded types, but they're there should you need to write very theoretically sound or extensible code.

This is one of my major grips about Scala, but sometimes I'm also guilty of overusing this feature how you do Google <:< or ~?> or λ. Its even worse when the api you are working against doesn't have a "normal" function for what you are trying to do. It does take a while to remember them but even worst it makes it hard for new users to follow your code. Reminds me of some for a lack of a better work "voodoo" Perl code way back.