I really like his book Ra. It's a great example of secret societies and layers within layers. Although to me it honestly sounds impossible.
I'd bought it while stuck in an airport trudging through Kim Stanley Robinson's Mars trilogy (which I hated), saw a book by qntm in my recommended list and bought it instantly, having read their online stuff. Unlike the KSR, it was great fun and I blazed through it.
I'm glad I've read it, but I doubt I'll return to it.
I'll definitely be looking for this as a book gift to myself.
I wonder if having books like this rewritten by an llm in a different style could reinvigorate poorly written / high concept stories.