The Wikipedia page for Anathem says:
Major themes include the many-worlds interpretation of quantum mechanics and the philosophical debate between Platonic realism and nominalism.
Unfortunately I think this makes it sound a lot cooler and more interesting than I actually found it. Maybe I’m too used to reading very dry material, but the excitement of the surrounding story didn’t do much for me in terms of extra caring about the “philosophical” ideas. I’d probably rather read nonfiction about real-world philosophy than fictional dialogues about semi-real philosophy except where a bunch of words have been replaced with made-up but similar-sounding words.
The basic idea of a group of people that intentionally only connect with outside information every N years was pretty interesting. I also found some of the branching narratives stuff fun. I thought things did get better in general closer to the end, but the final words of the ending struck me as lackluster in a way that no amount of self-awareness could really save.
Overall, this is one of those sci-fi books where I can see why certain people would really like it a lot, but I’d personally rather read the non-fiction equivalent about real-world versions of the topics being examined.