I was gullible enough once to eat up his philosophy. Because he's not trivially wrong. He tries to take credit for developments that aren't his, present good ideas mixed in with nonsense and you just swallow it all naively, unless you've previously thought through the stuff. His casual dismissing of the mainstream can become your style as well, and you can feel you become part of something special, something that transcends most people's levels. It's really not unlike Scientology.

Sorry if I come across as warning too much. It probably depends on your personality type. If you are a very reflective and self-critical person, you can tie yourself up with his philosophy I can tell you that much. Now, granted, the consequences of something don't tell much about the truth of that thing (just like the "God exists because if God exists then I feel safe and happy and gives meaning to my life" is a bad argument.), still - keeping in mind that we are discussing whether a novice should be advised to read Yudkowsky - I think there are better choices.

I absolutely think that if you're above average smart but lack the factual, lexical knowledge, then reading his stuff can be detrimental to your intellectual development. You're better off without it. Yeah, you can make the case for going through such experiences, just like you can make the case that going through drug addiction and recovery can make you a better/stronger person in some sense, but as a first approximation it's better to stick with mainstream literature. That's the main point I'm trying to argue for.

And I have to add that it's weird and frustrating to argue about this because obviously those defending his ideology are smart enough to come up with good counterarguments. It's nothing like debating with, say, Young Earth Creationists. These people (perhaps including you) are often intelligent, tech/math/CS-literate people. The point of disagreement is of a finer nature that is hard to even discuss because that whole aspect is usually dismissed as "useless philosophy".

It's somewhat akin to https://xkcd.com/793/ where someone who masters one technical field feels an immense power or superiority and becomes a bit smug.

Feynman had the cred to be able to say "If you don't like it [the way nature works], go somewhere else; to another universe maybe", but talking in this kind of confident way requires a very solid background. I'm not talking about prizes, simply actual results. And I know it's difficult due to the nature of the topic (studying a hypothetical unknown-probability event that can wipe out everything), but this sort of cop-out is just not convincing.