I first tried reading Anathem back when it was relatively new, but couldn't get past the first 100 pages or so. Now, having the benefit of a decade more worldly knowledge (such as the history of the Catholic church, Western philosophy, etc.), I've finally finished it and I can say that it was an incredible read.
Is it an collection of philosophy dialogue? Is it an action-adventure novel? Is it actually just Snow Crash presented differently?
Yeah, kind of, but it's also a book that gets exponentially more exciting as it goes on and also says some pretty profound things. (The profound things are, unfortunately, fiction, but it would be a high bar for an action-adventure novel to also truly advance philosophy.)
So if you're considering reading this, just know that you shouldn't worry too much about the made-up words - you'll understand them in due time - and that the crazy stuff starts happening 1/3 of the way through and even crazier stuff 3/4 of the way through.
In writing an action-adventure novel based on philosophy and physics though, I think the author has run into a bit of a conundrum: it's too rigorous for readers wanting a fun read yet not rigorous enough to hold together well when the crazy stuff starts happening. That is, he takes a long time to set up a theoretical foundation for what happens, but as he stretches the theory to advance the story, he stretches a little too far and leaves a lot of holes.