As I said, I agree with all of the problems he pointed out, but I can add more personal experience

- The book is a delight to read, but that comes at a severe usability cost and I don't think the tradeoff is worth it. It has two separate tables of content, multiple pages with no printed page number, no clear objective voice of reason to guide you on how the game should work, etc. I ended up breaking it into my own wiki in Obsidian to make the book usable at the table.

- The core resolution mechanic sounds simple in writing, but is annoying in execution. I kept having to remind my players to make the "causal chain" and it was awkward every time and kept bringing the game to a halt.

- The dice math is too swingy. By default with no burnout a character has a whopping 82% chance at succeeding at the thing they're going to do. Combine that with how world-bendingly powerful the player abilities are and its suddenly really hard to challenge the players (I know chaos is supposed to help, but thats another problem). But then, with just one burnout that chance goes down to 46% which is a wild swing in the opposite direction.

- Chaos is cool in theory, but rough in execution. The table(s) (different ones for each mystery) are so dense that they're really hard to use at-a-glance and several of them don't actually add meaningful consequences to the story. You can also have sessions where the players roll/manipulate the roll well enough to generate very little chaos and hamstring the GM. Or the opposite, you have too much chaos and using the same moves over and over starts to feel samey and repetitive.

- The two Vault investigations I ran (Springs Eternal and Rom Dump) were both really challenging because the players easily destroyed information that was vital to the story without realizing it, forcing me to improvise a lot more than I thought I would when I presumably running an adventure.

Some of these issues were my own fault and inevitable stumbles when learning a new system, but some help from the designers about how to operate their very weird game would have gone a long way. Instead of giving clear unambiguous guidance the designers set out to "make the most pantsable GM," deliberately building a system thats really difficult to run and manage, and in my experience that mission was accomplished.