All true but still, you could see I just started reading it and I'm new to the franchise.
(I wrote that post with a humorous twist, so it wasn't meant as an attack)
I wrote:
Valka D'Ur said:
Dune makes a satisfactory standalone novel. The protagonist succeeds and the villains are dealt with. The sequels that Frank Herbert wrote - Dune Messiah and Children of Dune complete Paul Atreides' part of the story, and that's the line where many Original Dune fans prefer to stop. God Emperor is a boring, miserable slogfest (unless you happen to love the character of Leto II, which I don't; I loathe him). Heretics and Chapterhouse feature Duncan Idaho (the one character who is present in all the FH-written Dune books).
My advice is to not waste even one nanosecond of your life reading anything by Kevin J. Anderson/Brian Herbert. It's all crap. I do recommend the Dune Encyclopedia, which was compiled by Frank Herbert's friend, Dr. Willis McNelly, and it had FH's approval (with the caveat that future novels might not align with some of the Encyclopedia's content, which was fair; the Encyclopedia only goes as far as God Emperor, as it was published before Heretics and Chapterhouse were written).
I don't actually think I spoiled much. There's much more I did have in my post that I deleted because it went into specifics that a new reader would not really need to know. The novel has an extensive set of appendices in the back, and I strongly recommend reading them. They will answer a lot of questions you might have.
I did say that Paul's story ends in Children of Dune, but I didn't (and won't) say how. It's not really a spoiler to mention this, due to the immense time jump between Children and God Emperor. There's another huge time jump between God Emperor and Heretics.
To find out how Duncan Idaho can be in all six books, you will have to read
Dune Messiah.

*
*Duncan Idaho is my favorite character
Oh, and please do NOT believe the BS claim by Kevin J. Anderson/Brian Herbert that
Paul of Dune is the 'direct' sequel to Dune. It really isn't, since it retcons and actually disavows the entirety of the events of the Dune novel (claiming it's just propaganda and never happened).
The original six books are:
Dune
Dune Messiah
Children of Dune
God Emperor of Dune
Heretics of Dune
Chapterhouse: Dune
There was supposed to be one final novel, but Frank Herbert died before he could finish it. Even so, Chapterhouse: Dune makes a logical end to the series even though there are a few plot points left unaddressed. KJA/BH's Hunters/Sandworms of Dune duology claim to be what FH was working on, but they're so badly-written, completely missing Frank Herbert's point about some of the critical characters, and are a blatant self-reference to their own inferior novels (as in you'd need to read those to understand WTH is even going on in parts of H/S) that I honestly do not recommend reading them.
Other Dune-related books I do recommend:
The Dune Encyclopedia: Compiled by Dr. Willis McNelly, who was Frank Herbert's friend. Herbert gave his blessing to this book, with the caveat that he would not be bound by it in future novels and could (as he did) change some things (the Encyclopedia was published after God Emperor, but before Heretics). This is the book that really explains the Butlerian Jihad, Fremen history, culture, and politics, the history and politics of the Imperium, the Bene Gesserit, and the Sardaukar, the ecology of various planets, and so on. Some articles are fluff - such as a story about a couple of Bene Gesserit sisters who work in their chapterhouse's laundry and one of them wins a trip for two to the planet of Gamont. What they saw and experienced on their holiday wasn't quite what they expected... One of the things I really enjoyed was the sheet music for a couple of Gurney Halleck's songs.
National Lampoon's DOON. It's a prose satire of Dune, and I found it hilarious. It's the best kind of satire - the sort that respects the source material.
Songs of Muad'Dib: This is a collection of poems written by Frank Herbert. Not all of them have to do with Dune. This one might be hard to find. I only have a copy because I ran across them in a local liquidation store (they evidently didn't sell very well, which is too bad).
Eye: This is an anthology of short stories and includes two special Dune entries: The first is Frank Herbert's retrospective of his experiences and impressions of the making of the 1984 David Lynch version of Dune (fans usually refer to it as "the Lynch movie"), and the second is a "walking tour" of Arrakeen for pilgrims who have come to pay homage to Paul Atreides, known as Muad'Dib among the Fremen. This book has some
incredibly gorgeous illustrations of the palace of Arrakeen, some of the characters (ie. Irulan, Mohiam, and Duncan Idaho), and Arrakeen as seen from the desert. The in-universe time setting for this walking tour would be during
Dune Messiah. The other stories in the book are not related to Dune.
Dreamer of Dune: This is Brian Herbert's biography of his father, Frank Herbert. I found it an interesting read, though of course I don't know if Brian embellished, changed, or omitted anything significant.