> Scala on the other hand suffers from an explosion of language features

This isn't what I feel. Scala's feature set is small, but powerful.
Some examples:

- Scala has no notion of static methods, unlike Java. Every reference or value is an object, every function call is a method call, with Scala's OOP being much, much closer to Smalltalk than any of the C++ inspired bastardizations tend to be

- Scala doesn't have special syntax for certain types, like Java's plus operator for Strings

- Scala's support for variance is much simpler and at the same time more powerful than Java's use-site variance by means of wildcards (I've met no Java developer that can tame Java's wildcards, I'm sure they are out there, I just haven't met them)

- speaking of variance, Scala's type-system has Null and Nothing and AnyVal and Unit; in Java you've got "void" as a special construct, in Java the primitives are special, in Java "null" has special and unexplained treatment, in Java Nothing is surely there somewhere in the implementation, but you can't use it ;-)

- Scala-async is a library, instead of a language feature like in C#

- Slick is a library, instead of a language feature like Linq in C#

- Scala's for comprehensions are much more general purpose than the foreach construct in Java, or than for comprehensions in Python, which means that Scala doesn't need new constructs for dealing with async stuff or with (god forbid) monads

- Scala's traits are much better and I might say easier to understand than Java 8's default interface methods

- Scala does not have side-effecting keywords such as break or continue

- Scala does not have the special indexing syntax of arrays

- Scala does not have special syntax for building arrays or maps, as the basic language is enough for doing that in an expressive way

- Scala does not have operator overloading, or operators for that matter; as in Scala the operators are just plain methods

And then indeed, we can talk about things like pattern matching or case classes, which in my opinion add tremendous value. But you know, static languages need features in order to be usable / expressive and cannot be minimal in the way that Scheme or Smalltalk are. For example people complain about implicit parameters, however implicit parameters happen anyway in any language (e.g. undocumented dependencies, singletons) and at the very least in Scala you can document those dependencies in the function's or the constructor's signature and have it statically type-checked and overridable. Plus implicit parameters allow one to work with type-classes and compared to Haskell, in Scala a type-class is just a plain interface and its implementation is just a value. And also the CanBuildFrom pattern is not a type-class and isn't possible in Haskell. So such a small feature such as implicit parameters yields tremendous power.

I could probably go on, just wanted to point out that Java's simplicity and at the same time Scala's complexity is entirely misleading. And also, I happened to introduce many rookies to Scala and by far the biggest hurdles are posed by exposure to new concepts or design patterns, brought by functional programming of course. Even explaining Future is problematic, a standard library thing that otherwise leaked into Java and many other languages as well.