I received House Harkonnen as a Christmas present in 2002 and two years later I finally got around to reading it. It is a brick of a book, which was the main reason for taking so long to get around to it. It looked uncomfortable and unwieldy. It turned out to be far less of a pain than I'd assumed though; and I haven't been working out since I got it.
I suppose you'd like to hear about the actual content now, right? Well. In many ways Brian Herbert is rather brave to consider writing the Dune Preludes series as he was bound to come in for a fair bit of criticism. I mean let's face it, Frank Herbert was a genius and the original Dune series are probably the finest Sci-Fi novels of the 20th Century.
The problem with writing prequels to such a masterwork is that surprises are going to be fairly few. You know that Leto, the Baron, Jessica, Idaho, Gurney etc can't die, because you know what happens to them a few years down the road before you even start.
To be honest, I found House Harkonnen to be fairly mundane and pedestrian. It failed to grip me and the writing is nowhere near the level of the originals. It isn't that it's a bad book or badly written really; it's more that it isn't written to the level of detail and intrigue as the originals. I find it hard to believe that the prequels are written to notes and synopses created by Frank Herbert. If this was the case, his notes were few and lacked of detail.
There's something about reading this novel that makes you feel the writers are losing momentum and the ideas aren't there anymore.
Having said all that, I did go through it pretty quickly. The pace is fast and the chapters fairly short, inviting you to read one more before turning out the light.
In summary: A readable book with no real surprises. I would have to say average, especially if you've read the originals.