A lot of the "OMG Scala <3" stuff being written recently comes from people who have written Scala books and therefore kind of have an agenda.

The essential idea behind the post is this: using a language like Scala can make you use a mainstream language like C# or Java differently. By using a language that makes immutability the default it teaches you when mutable state is actually necessary and when it isn't. This will lead you to write code in whatever normal language that also has less mutable state, and fewer side effects. It will therefore be easier to test and have fewer bugs.

And, no, I have not written any Scala books and have no Scala-related products/services to sell you.