I've read most of the Brian Herbert and Kevin J Anderson works.
the're just not the same. Often times they read like fanfiction at best. Many of the sequels in particular that were "based" on notes from Frank herbert seem so out of touch with the direction that Frank went with his books that he did write that it's unfathomable that it's what he intended.
the "final" two books in particular that were supposed to "finish" the original series feel so far out of left field that It doesn't actually even feel like "dune"
I also don't think Kevin J Anderson's writing style works for Dune. he's great for action, and adventure writing. He can keep up the pace for "fluff" style writing great. Thoroughly entertaining, but not very deep in meaning. And Frank herbert's writing was completely opposite of that. it was immensely deep, if sometimes slow in story progression. the opposite writing styles of the authors, combined with Brian Herbert's interpretation of the stories just always made that work feel... off.
I know that Frank was long dead when these books got started. But I feel like there might have been better choices out there than Briand and Kevin to finish off the story.
I really enjoyed the prequels - bought every new book in "hard cover" when first avaiable - especially the machine crusade era books because it was referred to in the originals and because I think Keven J Anderson is a terrific writer ( ie Assemblers of Infinity) etc