THE ILLUSION OF LIFEWhen it finally came out, I snapped one up and read it in a couple of nights. It turned out not exactly to be what it was promoted as. Most of the book was just propaganda for the Disney studio. It was a written history of the studio that claimed everything that was ever done with any quality or worth came from Disney, and no one else ever did anything good, or invented anything important. I don't know whether the writers actually believed that, but it came off as pretty ignorant, especially since it spent so much time talking about the things Disney never did well - like story and personality.
THE BEST CHAPTER IN THE BOOK
But there was one chapter that I thought was great: "The Principles Of Animation". This spelled out technically, the basic tools of how to make smooth animation. I wish the whole book would have been about this and had expanded each principle into actual methods and details.It does however in a very general sense explain fairly clearly what each of the animators' basic tools are.
The funny part is that while I agree totally in theory with what the importance of each principle is, I am also surprised that the Disney animators didn't actually practice all of them.
PRINCIPLES ARE NOT AN END IN THEMSELVES
I would like to add a point about principles or basic tools of animation - or any other trade. Your principles are merely the tools you use to create things with. They aren't an end in themselves. 
This is where I really part ways with Disney and today's Disney imitators. I have seen many movies and old time shorts that just seem to be soulless collections of principles, rather than works of entertainment or expressions of humanity. Like watching an expensive tool kit hammer gold nails, screw platinum screws, drill perfect holes but never actually build anything of any interest, fun or originality.OTHER STUDIOS PUT THE PRINCIPLES TO BETTER USE
I think Warner Bros. put these principles to much better use than Disney. The principles - or skills are just a starting point. You use them to express something of human interest. You have to add your own personal observations of things. Great entertainment isn't merely a matter of skill - but skill is necessary! The best art and entertainment glorifies the heights of human imagination and invention. It wows us. It leaves us breathless, makes us feel new things, leaves us in wonder of the the possible heights of human achievement. That's when it becomes art - or maybe even entertainment.
Disney cartoons (and many will disagree) seem to aim at having elaborate displays of all of these principles acting upon each other smoothly without any jerks and jitters. This quest for smooth perfection leaves out the real essentials of art or entertainment - a view of the world that is honest, engaging, exciting, original, bold and surprising.
soulless characters built up from animation principles and Disney stylistic cliches and formulaDECADENT DISNEY TRADITIONS
http://johnkstuff.blogspot.com/2007/02/being-enslaved-to-someone-elses-style.html
I also might disagree on the order of importance of the principles in "The Illusion Of Life".
THE MOST IMPORTANT DISNEY PRINCIPLES HAVE DISAPPEARED
I think "solid drawing" should be the first principle. "Appeal" second. Without those 2 essential ingredients, you are left with just flying blobs of amorphous but smoothly animated college exercises.I am going to try to illustrate each of these principles in a post, but by using some animation from other studios to show that you can apply them to other styles.
A big problem for those who love Disney's smoothness and execution, is that it is hard to separate the obvious strong principles from the Disney stylistic cliches, so that with each generation of "quality animation" we get more simplistic copies of Disney that focus more on a handful of cliched movements, expressions and designs - and even story structures. People copy what Disney wasn't good at, instead of what they really were good at.