I worked as a graphic designer professionally for awhile, and still do some graphics free lance work now and then, and I've struggled to understand Action Script for years.
I never took programming or scripting courses. I had to learn Flash and Action Script for an old job years ago, and I had to learn it on my own by reading books and online tutorials.
In the past, I've read a mountain of books on AS2 (Action Script 2) and so far only about three or four on AS3 (Action Script 3).
Out of the Action Script books I've read so far (for A.S. versions two and three), this book by Chun is one of the best.
I own several books about AS3, but have only read a few of them at this time.
As for version 3 alone, the one by Mr. Chun is *the* best one yet.
The other AS3 Quick Start Guide wasn't bad, either (it was entitled 'ActionScript 3.0: Visual QuickStart Guide,' by Derrick Ypenburg).
I've already read the first edition of 'Learning ActionScript 3.0: A Beginner's Guide' by Shupe and Rosser, but despite its title, that book is most certainly not for beginners; it was too complex and mainly seemed to focus on esoteric, not common tasks, one would do in Flash. (I wrote a review of the Shupe and Rosser book on Amazon.)
Another poor choice for beginner Action Scripters:
The "Action Script 3 for Adobe CS4 Professional Classroom in A Book" (and the CS5 version is quite similar to the CS4 one, both are published by Adobe Systems Inc.) offered lots of tutorials and exercises, but little in the way of explanation for how and why the scripts work, so I had to put that book aside temporarily so I could read this one by Chun.
This book by Chun covers most of the ordinary things you're likely to use Action Script 3 for, and out of all the AS3 books I've seen so far, it does the best job of clearly explaining what the code is doing and how it works and why.
I also like the fact that after Chun shows the reader a script, he often explains other uses for it - how you might use the script in another project and why.
I can't begin to tell you the number of times I've read A.S. books where an author shows a chunk of script, and all I can think of is,
'When would I ever want to use this concept or script? What is it good for?,'
but in some sections of the book, Chun explains multiple uses for some of the scripts he contains in the book, something which helped me understand the scripts better.
There were one or two small areas in the book that were unclear to me that I wished the author had explained differently or in more depth, but the vast majority of the book was very clear, and it demystified a lot of Action Script for me.
(As for the unclear parts: I did not fully understand the last couple of lines of script on page 465, in figure 11.37. There were one or two other brief areas later in the book that I didn't totally understand.)
Thankfully - yes *thankfully!* - in the chapters that discussed math, atans, cosine, radians, etc., the author kept the explanations short and simple.
Mr. Chun just gets right to what you're trying to accomplish in Flash with Action Script in the math chapters (and in other chapters covering other topics, too) and explains it in a straight forward manner, with straight forward examples - which is how I prefer to learn especially when math crops up in to the discussion.
In most other AS3 (or even in AS version 2) books I've read, the authors, for some reason I cannot figure out, "over-explain" these mathematical, trig, and geometry concepts.
What I mean is that some of the A.S. authors spend half to three-fourths of a chapter giving the reader a detailed history behind mathematics and the philosophy behind animation and movement, which only confuses me more!
(I was never any good at math anyway, nor did I ever take trig or geometry - just tell me how to get the dang movie clip to move in a circular fashion or whatever instead of spending pages on the boring theories behind math formulas, how to calculate the sides of triangles, how to calculate angles, or whatever. Or at least keep such discussions short and sweet.)
This author doesn't muddle things up and confuse the reader by tossing too much mathematical jargon or theory at them. He does explain the concepts behind the math a bit, but he gets to the point about it.
I am also very grateful that the author sticks to timeline based scripts only (this book will NOT teach you how to make classes and packages, which to me, is a huge bonus, not a detriment).
I have another AS3 book for beginners I began reading a few months ago (the title escapes me at the moment) where the author of this other book has the reader jump straight into using classes and packages in the first few chapters, and I find that approach totally confusing (so I had to put his book aside temporarily).
I much prefer Mr. Chun's approach in this book of teaching script that goes in the timeline only.
I think beginners to intermediate level learners are already confused enough by plain old time line Action Script 3 without forcing them to have to jump an additional hurdle of learning external scripting stuff (OOP, classes, packages).
I think the publisher really ought to market this book as more than just a generic Flash book.
This book does such an outstanding job explaining AS3, I think in future editions of the book, they should rename it to give it some kind of sub heading on the cover indicating it can help beginners or intermediate level types learn Action Script 3.
As it stands now, unless I had used Amazon's "search inside this book" feature on this book, I would have thought, just based on the cover only, that it's one of those basic introductory Flash books that only discusses the usual stuff, (such as how to use the paint bucket tool), and so I would've missed out on a great Action Script book.
If you are a beginner who finds Action Script totally confusing, I'm not saying this book and this one alone will do the trick. You may still need to supplement it with a few free online tutorials, or one or two other books.
However, take it from someone who has been intimidated by Action Script for years, and who has read many books about Action Script: this is one of the best books out there on the subject for anyone beginner to intermediate.