Erlang really appears to be an interesting language, and the author's enthusiasm for the subject shows - which is good. It helped me to keep going, when at times the code was a little hard to follow.
The book does a good job of introducing the language. In particular later chapters give emphasis to the topics of concurrency through multiple processes, multi-cores and distributed programs. All very timely subjects for a world that is connected to the Internet, and where even laptops have multi-core processors
I gave the book a 4 star rating because I feel the author somewhat forgot who his audience is.
On page 5 he starts out with a description that fit me almost perfectly, and probably many other readers: "Once upon a time a programmer came across a book describing a funny programming language. It had an unfamiliar syntax [...] it wasn't even object-oriented. The programs were, well, different....Not only were the programs different, but the whole approach to programming was different."
After reading the book I don't feel like the "Erlang Master" that the road map described (pg 9). While the syntax is now familiar, I still look at the Erlang code and it feels foreign. I still have to "decipher" the code instead of read it.
I would have liked the book to more fully address the items from the "Once upon a time" paragraphs. Being that "the whole approach to programming" is different than the OO that many readers are used to, I would have liked to have seen a chapter (or three) on how to best get into that mode of thinking.
I do think the book is a good jumping off point. It gives you more than enough to get started.
However, if you are unfamiliar with languages where functions accept functions which also accept functions as parameters and return another function as a result, you may end up feeling (as I did) that you only have half the puzzle.