The fact that it's not an easy thing should be appreciated when you look at how e.g. Brian Herbert's continuations of his father's writing were received, and is one of the reasons Rhianna Pratchett would rather write more video games (most notably the original Mirror's Edge and the latest Lara Croft reboots) than more Discworld.
Brian Herbert always struck me as cashing in on his father's popularity, rather than trying to augment the original vision. Frank Herbert took pains in the original Dune series to not spend time detailing the backstory of the Butlerian Jihad period of the world's history: to him, it was unimportant. For Brian to then explicitly devote a prequel trilogy to it gives it about as much weight in my eyes as a Star Wars Expanded Universe novel.
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.
Here's the most damning-with-faint-praise thing I can think to say, and it's true: I thought the House books (before the Jihad books) were the least bad things Kevin J. Anderson has ever had a hand in.
Christopher Tolkien, unlike Brian Herbert, was a distinguished literary scholar of his own right. I tried to get through Paul of Dune, but it's drivel. And I'm a pretty forgiving reader, having devoured plenty of dreck and enjoyed it (like the Hunger Games trilogy for example).
> having devoured plenty of dreck and enjoyed it (like the Hunger Games trilogy for example)
I'm surprised you consider the Hunger Games to be dreck. They're clearly books for teenagers, but have a strong voice, and have the honesty to show the costs their characters paid for their heroism.
Brian Herberts books, the Game of Thrones final and from what I've heard the last Star Wars movie all have their detractors but personally I'm thankful for at least giving closure to the overall story arc. It might not be good but at least it's over.
I also liked some of Brian Herberts books, particularly the prelude series. Legends was horrible and I think the series could have ended fine without the backstory.
I reread the Dune series last year. I knew of, but nothing about, the Brian Herbert books other than that a handful existed. I was pretty surprised and very disappointed to see how badly they were panned. Clearly not another Chris Tolkien situation.
I enjoyed all of the prequel books. They have a more modern feel to them when compared to the classic Dune novels, so that's what may turn some people off.