Update: See my unendorsement of the Deutsch books.
Everyone should learn this stuff, but currently only a handful of people in the world know much about all four of these books. This material is life-changing because it deals with broad ideas which are important to most of life, and which challenge many things people currently think they know.
However: they’re way too deep and novel to read once and understand. The ideas are correct to a level of detailed precision that people don't even know is a possible thing to try for. The normal way people read books is inadequate to learn all the wonderful ideas in these books. To understand , there’s two options:
1) be an AR or DD yourself, be on their level or reasonably close, be the kind of person who could invent the ideas in the first place. then you could learn it alone (though it’d still involve many rereadings and piles of supplementary material, unless you were dramatically better than AR or DD.)
this is not intended as an option for people to choose, they're like one in a billion kind of people. and even if one could do it, it’s way harder than (2) so it'd be a dumb approach.
2) get help with error correction from other people who already understand the ideas. realistically, this requires a living tradition of people willing to help with individualized replies. it’s plenty hard enough to learn the ideas even with great resources like that. to last, it has to educate new people faster than existing people stop participating or die. (realistically, this method still involves supplementary material, rereadings, etc, in addition to discussion.)
What is the current situation regarding relevant living traditions?
for the DD stuff, there’s only one living tradition available: the Fallible Ideas community.
the most important parts of the DD material is based on Karl Popper's philosophy, Critical Rationalism (CR). there’s some CR-only stuff elsewhere, but the quality is inadequate.
besides reading the books, it's also important to understand how the DD and AR ideas fit together, and how to apply the cohesive whole to life.
there's lots of written material about this on my websites and in discussion archives. the only available living tradition for this is the Fallible Ideas community.
for the AR stuff, there are two living traditions available which i consider valuable. there are also others like Branden fans, Kelley fans, various unserious fan forums, etc, which i don’t think are much help.
the two valuable Rand living traditions disagree considerably on some topics, but they do also agree a ton on other topics.
they are the Fallible Ideas community and the Peikoff/Ayn Rand Institute/Binswanger community. The Peikoff version of Objectivism doesn’t understand CR; it’s inductivist. There are other significant flaws with it, but there’s also a lot of value there. It’s has really helpful elaborations of what Rand meant on many topics.