Roughly in the order I'd recommend consuming them.
Dave Thomas - Power of Erlang, Joy of Ruby - https://www.youtube.com/watch?v=lww1aZ-ldz0
Dave Thomas Elixirconf Keynote - Think Different- http://www.confreaks.com/videos/4119-elixirconf2014-opening-...
elixir-lang.org tutorial - http://elixir-lang.org/getting_started/1.html
Programming Elixir - https://pragprog.com/book/elixir/programming-elixir
Awesome Elixir - Curated list of great libraries - https://github.com/h4cc/awesome-elixir
Elixir In Action - http://www.manning.com/juric/
Learn You Some Erlang For Great Good - http://learnyousomeerlang.com/
Erlang and OTP In Action - http://www.manning.com/logan/
I haven't had a chance to read McCords new book, but having read his code and interacted with him a fair bit in #elixir-lang the last few months I can only assume I'll be adding it to the bottom of this list as an important intermediary step to becoming proficient in Elixir along with learning OTP.
And yea, you're not going very far without digging into OTP, and Martin Logan's book is pretty excellent. Great entry on this list.
If something needed to be wrapped to make it play more nicely with elixir, for example to change argument order to better suit elixir's |> operator, or if there were other real benefits to wrapping an erlang library, then they might wrap it. Otherwise if the erlang library is good just use the erlang library.
But my main point was that when I started, I could just look to one source for language docs.
But as I dug in, I realized that to do a lot of things, I needed to look at Erlang too. And then I realized I had to understand it.
It's not bad, it's just a thing that makes learning the awesome language a lot more difficult.
For me its all about OTP, thats the difference maker with Elixir/Erlang, without that its just another functional language, with it is an incredibly powerful tool/framework for building impressive distributed fault tolerant systems.
That being said, I think there needs to be a communal effort to improve Erlang documentation. It is very terse. One of the points brought up in Garret Smiths talk: https://www.youtube.com/watch?v=3MvKLOecT1I
I know were you're coming from though, its a really good preso with surprisingly bad recordings.
Rubyists! Have a sip of Elixir – http://www.confreaks.com/videos/5078-RubyConf2014-rubyists-h...
Ruby + Elixir – Polyglot FTW! – http://www.confreaks.com/videos/3845-rdrc2014-ruby-elixir-po...
Also, I'm writing a book on Elixir – http://www.exotpbook.com
Finally, I've done a few posts of Elixir – http://benjamintan.io/blog/tags/elixir/
For me, metaprogramming is one of the things that was a deciding factor with Elixir, in addition to all the other functional programming aspects that are part of the language. I'm most definitely not an amazing polyglot with a wide degree of experience with every single functional language out there, but this feature pushed me to invest time to learn Elixir. Metaprogramming has saved me immense time in numerous applications in Ruby. So, I consider it a critical thing to learn.
Of course, after investing time in Elixir you very quickly learn the power of the Erlang VM. Elixir is like a gateway drug! I now have a consistent mix of Erlang and Elixir syntax in the stuff I'm playing around with. One of the chief complaints for people with Erlang is the syntax. Elixir makes the entire proposition of learning Erlang far more appealing...and then you really it is all actually Erlang under the hood!
And, one of the big things that Elixir adds on top of the Erlang VM is metaprogramming. There aren't a lot of great sources out there on the subject. Chris's book is a great addition to the slowly growing Elixir library.
However, if you are going to use (and abuse) this powerful feature of Elixir, I can't think of anyone better than Chris McCord to help guide you on your way. Chris' talk on Macros at Erlang Factory last year was not only highly education, but also very entertaining. If that video doesn't convince you, I recommend you take a look at the Phoenix web framework codebase. Chris is an incredibly talented programmer, and an incredibly helpful, and patient guide to those less skilled than he attempting to contribute code to his projects (I know this because he held my hand through getting a pull request merged into Phoenix some months ago when I was still playing with Elixir).
That said, this should not be your first Elixir book (as Chris points out in the book's introduction). It should be your second, especially if you are interested in writing libraries.
You can get a taster of it by watching his keynote at ElixirConf.