I don't see anything of substance here, besides a lot of pretty graphs. Just like Wolfram's "A New Kind of Science", we have the problem that there is a vast gulf between what you need to make flashy popsci and what you need to make a real physical theory. In increasing order of difficulty, you need to:

1. make a set of dynamical rules that matches general relativity in the low energy limit, such as recovering Lorentz invariance and the Einstein field equation (this is supposed to be the easiest part -- without at least doing this, a theory of everything is worth less than the graph doodles in my middle school notebooks)

2. demonstrate that you can add something that looks like matter

3. reproduce effects that we know have to appear in quantum gravity in the semiclassical limit, such as Hawking radiation and black hole entropy

4. demonstrate that you can add matter that behaves like the Standard Model

5. make specific predictions that we didn't already know from purely semiclassical considerations

6. find a way to verify those predictions

7. have the predictions actually be correct upon verification

These 7 steps are hard, which is why nobody has managed to do them. But it looks like Wolfram hasn't even bothered to start on step 1. His new book is just hundreds and hundreds of pages of pretty graphs and big words. It's more akin to a reformulation of the foundations of mathematics than a theory of physics -- and it's not a particularly good one, at that.

It's the same complaint I have about category theorists trying to do applied physics. (And category theory is a much more powerful language than Wolfram's!) Yes, you might have an incredibly general language, with which you can talk about vast swaths of possible physical theories. But we already had way too many possibilities using ordinary mathematics! We need to narrow down on specifics, not muddy the waters by making things even more general. I mean, it's like trying to rescue a startup by translating the documentation into Esperanto.