I think the split is between people who knew about cellular automata before reading the book, maybe even simulated their own cellular automata, and those who we

I think the split is between people who knew about cellular automata before reading the book, maybe even simulated their own cellular automata, and those who weren't familiar with the concept before. If you're in the former group, you'll find a lot of needless hyperbole about fairly standard results that were known for decades. Plus a few interesting ideas mixed in between. Plus even more hyperbole. If you're in the latter group, and didn't really know what cellular automata are about, your mind will be blown (and rightly so, these things are cool), and you won't mind Wolfram's tone so much.