I see no reason to believe Brian Herbert's claims that the work he has released (mostly farmed out to Kevin J Anderson) is actually based on anything real from his father's notes. If they are, he ought to release those to the public so we can form our own judgement. The Brian Herbert books are simply awful, and don't seem consistent with his father's work to me at all.
Christopher Tolkien released extensive amounts of his fathers drafts and brainstorms. It's fascinating material, and underlines the integrity of Christopher Tolkien and the love of his dad's corpus.