I was asking myself a question - do we really need another book about Elixir? I mean - there are not that many already present, but those that are represent a truly remarkable quality ("Elixir in Action", "Programming Elixir"). So, what's the point?
Fortunately this book aims a specific niche (& it helps to make it stand out a bit) - it's far less about Elixir & far more about OTP (the platform). Intro to the language itself does not cover everything, just what is need to start playing with OTP. OTP part doesn't cover everything either (it focuses on GenServer & supervising mainly) - but it good & comprehensive enough to show the reader the key possibilities & advantages this platform enables. It doesn't go as deep as Cesarini's book ("Desiging for scalability ...") but it not the goal.
Ok, so you know what book is about - but is it worth buying? If you're new to the platform & you're more interesting in distributed systems built on actor-model than the "beautiful language" approach that is a common value that guides development of Elixir as a language, than it's a book for you. If you've already went through any of the books mentioned above, you won't benefit much of it.
In general - very approachable, well edited, good code examples & illustrative pictures.
I'd give 4.5 stars, but I'll give 5 - just because it's Elixir & OTP ;D