[Negative1]

Maybe I'm in the minority on this but I felt this guide by twitter was poorly written. It has good coverage but concepts were just not explained very well.

The way I learned was reading from front to back "The Scala Programming Language" by Martin himself and starting a new project completely in Scala (which I'm launching soon). I'm sure that's not the best approach for everyone but using Scala in a practical environment in an idiomatic way really helps ground the concepts which can at first seem intimidating and difficult to comprehend.

Mastery is a whole other story...

p.s. I recommend Scala Cheatsheet if you are just learning: http://docs.scala-lang.org/cheatsheets/