Alex Payne: I think programmers who’ve never worked with a language with pattern matching before should be prepared to have that change their perceptions about programming. I was talking to a group of mostly Mac programmers, largely Objective-C developers. I was trying to convey to them that once you start working with pattern matching, you’ll never want to use a language without it again. It’s such a common thing that a programmer does every day. I have a collection of stuff. Let me pick certain needles out of this haystack, whether its based on a class or their contents, it’s such a powerful tool. It’s so great.
Robey Pointer: I wanted to talk a bit more about starting to use Scala. It definitely wasn’t a flippant choice we made over a few beers one night. We actually agonized over it for quite a while. Maybe not agonized, but certainly discussed it for a long time. One of the biggest draws for us to Scala as opposed to another language, was that once you’d started writing in a really high level language like Ruby, it can be difficult and kind of annoying to go back to a medium level language like Java, where you have to type a lot of code to get the same effect. That was a really big draw for us. With Scala we could still write this really high level code, but be on the JVM.
That's from an Artima interview about the guys behind Twitter evaluating Scala.
It sounds about right to me. Scala is adventuresome in the high-level features it gives you access to, e.g. pattern-matching, higher-order functions, and mixins. However, it runs and is integrated with the JVM, so you can always use a Java library or write in low-level Java if you run into performance issues or need some API that Scala doesn't provide.