I've been a fan of Neal Stephenson's since I first picked up Snow Crash. His books have all just been excellent sci-fi adventure stories, where he creates a compelling world to set the action in and fills it with interesting characters. Unfortunately, many authors miss one or the other of those points, so I feel it's important to stress. Even The Big U, which was probably the weakest of his novels, did a good job with both sides of this equation. So, when Anathem was announced, and the trailer was released, I was excited.
Now, I had almost expected that this novel was going to follow in a similar theme to Cryptonomicon and the Baroque Cycle, in that it would be historical fiction centered around the Shaftoes and the Waterhouses. While my understanding is that Stephenson intends to revisit that timeline, I was pleasantly surprised to find that Anathem had nothing to do with that timeline and was fresh and new and refreshing.
So what is Anathem? As the trailer says, it takes place on a World that is not Earth, in a Time that is not Now (okay, so that's a thinly veiled rehash, luckily, I don't think Stephenson wrote it). It takes place on a world called Arbre, which is similar to ours, or rather, it appears it was similar to ours at one point. At some time in the distant past on Arbre, the average joe became too afraid of Science, and what was happening in the world, so they took all the smarter-than-average people (and orphans) and crammed them into huge citadels, known as Concents, where these people, who became known as the Avout, were free to pursue their scholarly desires, outside of the control of the outside (Saecular) world.
Further, the Avout had separated themselves based on dedication, as well as taint by the Saecular world into four sects. One sect could leave the Concent every year, and was similar to a college in that wealthier, educated people tend to come for a while to study and then return to normal life. Another leaves every decade, another every century, and one every millennia. Further, these groups can only intermingle during a ten day yearly celebration (but only if their group would be able to leave the grounds in the first place). The story follows one young avout, Erasmas, and begins the day before the new year in 3890. Erasmas, being a Decinarian will be able to leave the Concent for the first time in ten years.
The world inside the concent (Intramuros) seems very monastic. Everyone wears robes, they study and discuss, they sleep in cells (rarely in the same cell from night to night), they grow their own food, and take turns at the chores necessary for the running of the concent.
The world outside the concent (Extramuros) seems awfully similar to our world of today, with bright screens, cell phones everywhere, and huge interest in movies and television. The only difference is that many of the people who would do science are hidden away, where the public feels they can do no harm. At one point, Erasmas comments on how very little progress has been made Extramuros in the nearly 4000 years since the Avout were locked away from society.
However, the world needs it's educated people from time to time, and as this would be an awfully boring novel otherwise, the book is centered around one of those times. The Saecular world becomes aware of an alien spaceship orbiting Arbre, and calls for a Convox, a gathering of Avout from across the globe, to determine what to do about it. Erasmas and his friends are called into this Convox.
The book, like Stephenson's others, takes a fascinating direction in that it occasionally digresses into Mathematical proofs and the nature of the universe. Unlike Stephenson's other novels, some of the longer proofs, which are generally less important, are put into the appendix of the novel, however, I would suggest reading them. It's a peculiarity of Stephenson's. Whereas Tolkien would take a dozen pages to describe a landscape and some bizarre historical tidbit which carried little relevance to the story at hand, Stephenson will occasionally do that with Mathematical Proofs. While some of the exposition can seem tedious, it's absolutely worth following it through for the story.
Anathem is not Stephenson's best work. For that, I'd probably have to say The Baroque Cycle. But the Baroque Cycle was three novels the length of Anathem, and that may well have something to do with it. However, while it's not his best, it ranks easily on the high end of my scale of Stephenson's novels. It's a great read, an interesting world, and the philosophical questions asked regarding the nature of the universe, and how we can describe it are interesting.
The climax of the story has a rather frustrating element, surrounding a Millenarian by the name of Jad, but while it feels as if there were loose ends surrounding that character, it was clearly done purposefully. Stephenson loves to introduce characters who have a seemingly mystical understanding of the Universe, and he never goes as deeply into that character as you might wish. In Cryptonomicon and the Baroque Cycle, it's Enoch Root, here it's Jad. Many will likely interpret these characters as having traces of the Divine, it's certainly easy to do so.
I'm not sure that's the only interpretation. It seems to me that Stephenson is arguing for the ability of Man, if Man could completely understand the universe, to possess a level of control over the Universe that exists outside of technology. As if, by possessing a certain level of understanding, Man could be as God. To go Biblical with the idea: Adam and Eve, in most translations I'm familiar with, ate but a single bite each of the fruit of the Tree of Knowledge, giving them some understanding of the world. The serpent had told them that to eat of the Tree of Knowledge would make them as powerful as God. The little bit of knowledge they'd accepted had scared them, and they stopped, but if they had kept going...
Even if you're not interested in the Math, Science, and Philosophy presented in the novel, the story is still a fun story, with interesting characters. But the meat of the story is definitely in the questions it asks, or perhaps more so in the questions it chooses not to ask directly.