Korzybyski wrote Science and Sanity in 1933 and as such specific things he says about the brain turned out to be false. I don't think you will find a single person who wrote at the time who made no mistakes. Technology such as fMRI did allow us to discard a lot of ideas about the brain as wrong.
Is that all wrong? Is there substantially more to Korzybyski and "General Semantics"?
A bit above you mention that "is" can be a treacherous word. Yet you started both of those question with it. From the General Semantics perspective your insight that "is" is can be a treacherous word didn't help you.
It's a bit like teaching someone Bayes theorem. It's quite easy to teach it in a way that someone can use it in textbook problems but it's quite another thing to teach it in a way that someone actually uses it in daily life.
Someone well trained in General Semantics and who uses that framework as his default way of reasoning about the world wouldn't ask "Is that all wrong?". Discussion whether the rejection of that question is pseudoscience bring you again near the space of what Korzybyski calls flawed Aristotelian reasoning.
Of course when I speak about that way and ask whether or not your statement is Aristotelian in nature, I'm also using binary categories. That makes it easier to make my point, but at the same time I'm not moving inside the rules of the General Semantics framework. In Science and Sanity Korzybyski mostly tries to present the arguments for General Semanitcs in it's own logic. That makes the book very hard to read.
As far as the charge of being poorly organized and verbose goes, it comes from the book being hard to understand. Korxybyski didn't write in a way that's easily accessible. If he would have the world would likely look different.
As far as the charge of not having influenced anybody goes, Albert Ellis who developed Rational emotive behavior therapy (REBT) with is one of of Cognitive Behavior Therapy does say that he was influenced by several of Korzybyski's ideas when developen REBT.
He has also influenced a lot of other important people. There's a list at Wikipedia.
I don't think you will find a single person who wrote at the time who made no mistakes.
Nor am I looking for one. I'm extremely uninterested in questions like "was Korzybyski a very clever person?" and much more interested in ones like "does the stuff Korzybyski wrote contain enough insights I currently lack, and little enough distracting wrongness, to be worth my while reading?".
A bit above you mention that "is" can be a treacherous word. Yet you started both of those questions with it.
Yup. There is no valid inference f...
http://esr.ibiblio.org/?p=6549