Since it's already been five years, it might be worth considering Erlang instead of Elixr. I'd recommend Programming Erlang: Software for a Concurrent World. It was written by Joe Armstrong who designed Erlang and "sold" it internally across Ericsson to people who were not programmers. They were people who were using Erlang to solve some other problem.
The paradigm of Erlang is message passing. The primary idiom is logic programming (like Prolog). Functional programming is related to logic programming. Between message passing, logic programming, and simple primitives for concurrency; Erlang programs tend to look a little strange. But it all hangs together in a way that has been field tested for thirty years. Erlang is a language that was engineered for use by engineers for solving engineering problems.
Elixr is mostly a way of avoiding learning Erlang and making the Beam VM popular. It is a procedural programming abstraction layer. For me, Elixr's abstractions generate an impedance mismatch and Erlang's syntax better expresses the engineering mechanisms of concurrent systems and logic programming. YMMV.
I've tried learning both and Erlang seems to be less magical and more consistent. That said, I wouldn't dare to start an important project in either language for the fear of getting stuck somewhere along the way. With Go, there are no such concerns, even though the language itself is by far less elegant.
A valid concern but you should have in mind that ElixirForum is one of the friendliest and most helpful programming communities that you will find out there. And that's not coming from me or Elixir veterans but from a ton of newbies, regularly.
The paradigm of Erlang is message passing. The primary idiom is logic programming (like Prolog). Functional programming is related to logic programming. Between message passing, logic programming, and simple primitives for concurrency; Erlang programs tend to look a little strange. But it all hangs together in a way that has been field tested for thirty years. Erlang is a language that was engineered for use by engineers for solving engineering problems.
Elixr is mostly a way of avoiding learning Erlang and making the Beam VM popular. It is a procedural programming abstraction layer. For me, Elixr's abstractions generate an impedance mismatch and Erlang's syntax better expresses the engineering mechanisms of concurrent systems and logic programming. YMMV.