Isn't that just a bullet point list of the whole book or specifically the new sections only? I'd say these were already covered when I've read snippets of previous versions.
If it's anything like the jump from version 1 to 3,* Toole will have incorporated the intervening ten years of additional academic research since the prior edition was published. And he will have read many of the misreadings of the prior edition on the internet, and he will spend considerable energy clarifying the sections that have been misconstrued.
For example, in the third edition, he addressed the position often erroneously attributed to him that room treatment especially first reflection point treatment is bad. His view, like the research it is based on, is far more nuanced than that. (And he even has a whole section about using room treatments!)
Further, it appears that there are whole new sections written by additional authors this time around.
People seem to forget that most of the content isn't Toole discussing his own research. Rather, he is bringing together the work of hundreds of other people in the field, not just summarizing his own work.
Looks like the new edition will take this even further by having sections written by other leading researchers, as well.
But my guess would be, as your question implies?, that if one is conversant in the third edition, from a practical standpoint, you will be familiar with the majority of what the fourth edition discusses -- especially if you are an AES member and have kept up to date for the past decade on the latest research and findings.
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*I talk about the jump from version 1 to 3 and ignore the so called "second" edition, because the second edition was just the first edition reprinted by a different publisher. 
www.routledge.com
