Using Scala has been a breath of fresh air after 10+ years of (mostly) Java. Mountains of boilerplate (I'm looking at you getter/setter/constructor auto-generated code) become 2 or 3 lines, in some cases a 1 line class definition:

  class Foo(var x: Int, var y: Int, var name: String)

(Thats equivalent to 6 method definitions and a constructor in Java. Also, the possibility that you forget to initialize one of the fields in your constructor [which happens from time to time in most Java code] is removed)

It's not just about having to write less boilerplate, it's also about having to read less code and expressing ideas using functional concepts where it makes sense.

Critics like to complain that having many features makes the language complex. In practice Scala code is fairly straightforward, the extra features just mean that library designers have to power to implement some pretty amazing interfaces for you using these features. Most Scala code is pretty sensible, and it's nice to know that the extra expressive power is there when you need it.

This may sound like heresy but I find myself being more productive in Scala than in Ruby. Part of that comes for the self-documenting nature of static typing and clear interfaces (No more "what methods and fields does this Foo object that is being passed in to this obscure method have?"). This is a very useful property to have when reading other peoples' code. The tooling is surprisingly mature (IntelliJ).

In hindsight picking Scala as a better Java should have been a no-brainer.