This book should probably be on any short list of the century's most influential books but would, ironically, never make a list of most read books. A significant number of people did read and internalize the book's message and Korzibsky's thought thus found its way into a number of diverse fields. But despite the wide dissimination of the book's message, the book itself, because it is so dense and difficult, has never had a wide reading audience. In fact, early critics made the point that a book about language and meaning should not have such difficult language that its meaning is difficult to understand. Yet this is the problem that Korzibski faced - having to use language to demonstrate the inherent limitations and dangers of language.
I have read the book, having come to it from a number of popular treatments of Korzybski's work. These at least provided a framework for understanding what otherwise might have been lost to me in the author's stiff prose. The book's most basic message, that 'the map is not the territory' (the Word is not the Thing it represents), can seem trivial when stated simply. However, only a little analysis will suffice to show how easily even very bright people fall into the trap of the 'Is of identity' - the semantic error that is inherent in the syllogistic form of reasoning that makes use of statements of the form 'All A are B, C is A, therefore C is B'. Note that 'is' suggests, and indeed often is taken to be, a statement of identity - that category A is identical in some ways, to category B. This is false. As words, these simply stand for, or 'point to' certain things, which themselves are identical only on the verbal level - the level of conceptual thought - not on the non-verbal level of external reality. Because we must use language to think and communicate with others about that external reality, we always run the risk of confusing what we say about things with the reality that exits independently of our thought.
The full implications of this line of reasoning is vast and extremely important. From the easy to see fallacy of reification, where having a name for something lends it a reality which in fact might not exist, to more complex issues having to do with the levels of abstraction inherent in various forms of thinking/speaking, this book touches on such a multitude of important topics that it is impossible to sum up in a few words.
Those new to the concept of General Semantics might do well to start with one of the popular treatments of the subject such as Hiakawa's Language in Thought and Action. But if one moves on to the primary text the rewards will be many. It 'is' a difficult book, but deeply rewarding