I had a difficult time learning much from this book.



One problem is that the author doesn't explain things systematically. Typically, a new concept is introduced without being defined, and some code examples are then presented. This gave me only a rough idea of what that particular language feature does.



Another problem is that there's no summary of the language - not even a grammar showing its syntax. So that when I encounter a feature (or a punctuation token that I haven't seen yet), it's hard to find an explanation.



The book reads as if it's a stream-of-consciousness collection of topics the author finds interesting. I don't know how this came about, but I would like a book that explains a new idea by first presenting the ideas that the new one depends on.



There are quite a few typographical errors and un-grammatical sentences in the book, which leads me to believe it wasn't carefully edited. There are also places in the book that use prose that conveys only an approximate idea of what's going on. For example, from page 235:



"The | operator also takes two of these combinated function thingies and combines them into a single function thingy..."



Overall, the book just seems to be not very carefully written. Having had no previous knowledge of Scala, I now have a rough idea of what Scala is, but if I ever need to learn the language, I'll have to find another source of information.