(Disclaimer -- I haven't purchased the Sand Omnibus, at least through Amazon. I did individually purchase, read and review each of the five parts and also purchased a paperback copy of the omnibus from Hugh directly.)
With that out of the way, I can honestly say I was blown away by SAND. I loved reading the book in the installments as Hugh released them, but will love reading them all together as a completely separate experience once I receive my paperback in the mail. After I read Part 5 and reviewed it, I said SAND > WOOL and I'm sticking by it almost a week later. The book is just magnificent and Howey once again shows off his masterful storytelling with an imaginative dystopian world that is all at once hard to fathom and easy to believe all at once.
Hugh calls SAND the antithesis to WOOL and I can see that clearly. While WOOL is about the absolute control that a small group of people can exert upon the masses, SAND is the opposite. It's what happens when there is no clear authority and yet people live, work, and die -- all under the invisible thumb of some unknown force.
In my review for Part 5, I mentioned two themes that resonate throughout the book. One of which is that lack of control yet oppression exists. The second is family. There are multiple main characters in this book, and yet they are all family and are all well-thought out and complementary to the story. Hugh does an amazing job of tying the stories of all these family members together so that in spite of all of the terrible and regretful things they have said and done to each other over the years, in the end, it all comes back to family.
There are a lot of parallels to WOOL. There are five parts, yes. There is a strong female lead character, yes. Perhaps the most striking for me, however, was the first part. WOOL would not exist as a book without that intriguing first part with the Sheriff wishing to go outside -- and yet, Sheriff Holston is not a major character after that. There is a similar aspect to SAND, but the story really gets cranked up in parts 2 and 3 before heading for a crescendo in part 4 and an epic conclusion in part 5.
Like I said, I've ordered the paperback from Hugh directly and I cannot wait to have it in my hands and rediscover the futuristic world that Howey has created for us this time. If reading Hugh Howey is wrong, I don't want to be right. Tremendous accomplishment, Hugh, and thank you.