Transformers: Exodus: The Official History of the War for Cybertron claims on its dust jacket to be "everything fans ever wanted to know about one of the fiercest rivalries of all time". In truth, Alex Irvine goes the route of Kevin J. Anderson in his novel Last Days of Krypton, creating a new history of Cybertron that combines some of the best elements that various writers have created over the years. While the book has a few flaws that make it tricky for someone new to the Transformers mythology to pick up and enjoy, fans of any of the series' many incarnations will find it a worthwhile read.
The book begins with Orion Pax, the future Optimus Prime, operating as a simple data collector for the Cybertronian archives. As part of his duties, he collects and becomes interested in a gladiator named Megatron, who agitates against Cybertron's rigid caste system and insists on the right of self-determination for all Cybertronians. Orion Pax is inspired to join Megatron's cause, quickly rising to become a leader in his own right, as schisms in the two robots' beliefs threaten to bring them into conflict. Fans of the series can guess where things go from there.
Transformers: Exodus doesn't take place, so far as I can tell, in any established Transformers continuity, although it might fit in with the recently released War for Cybertron video game. Many of Cybertron's historical elements are taken from the live-action movies, but there are plenty of concepts borrowed from the comic books and cartoons as well. Fans trying to fit the book into any existing series are going to end up with a headache, so it's best to just shrug and consider this another entry in the Transformers multiverse.
Happily, all of the concepts are used thoughtfully, so there shouldn't be too much for fans to gripe about. Cybertron in the novel is a stagnant world, long since settled into a pattern of decline. The legendary artifacts are history are mostly forgotten, or at best regarded as myths. Every Cybertronian is assigned a role at birth (which we finally get to learn something about) by the leaders of Cybertron's castes, and carry out that role for their entire existence.
In this sort of background, it's easy to identify with a revolutionary, as Orion Pax quickly discovers. The first part of the book takes a fascinating look at the alliance between Pax and Megatron, both of whom have similar goals, but vastly different ideas about how to achieve them. If there's any disappointment here, it's that we only get a cursory look at Megatron's motivations, and he comes off as a too-obvious villain. The reader knows that's where he's headed, obviously, but I would have liked the chance to identify with him more than I did.
The second part of the book is a longish interlude in which a Cybertronian historian describes the main thrust of the civil war between the newly-created Autobots and Decepticons. While it would have been nice to see the war from the perspective of the robots fighting it, there's simply too much conflict to handle in a reasonably-sized book. You do get an idea of the level of destruction being committed, and the interlude sets the stage nicely for the final part of the book, which chronicles the war's closing days.
By this point there's no real hope for peace between the two factions, and the last part of the book focuses on the discoveries of various hidden artifacts by both sides. One of the few truly new additions to the Transformers mythology is introduced here, in the form of a new power source that poses devastating consequences for the planet Cybertron. While interesting, it's hard to build up any real sense of concern about the threat this new power brings, simply because the reader knows the gist of what's going to happen in advance. One of the brilliant touches in Last Days of Krypton was Anderson's ability to make the reader believe, or at least hope, that events would play out differently then the reader knew they would have to. Here, the final result of the civil war is pretty much a foregone conclusion, and there's nothing to suggest any other possibility.
The characters are all fleshed out well enough to fit in with what fans already know about them, but generally not deeply enough to incite any strong feelings for them. Given the size of the cast, this isn't really a surprise; and to the book's credit, a lot of fan-favorites turn up, with none of them being handled badly. Orion Pax is probably the book's strongest character: his journey from data clerk to leader of a planetary-scale army is fascinating, and carries through the entire book. Among the villains, Starscream is the big winner, portrayed as his usual treacherous, scheming self, but with enough competence to make him a valid threat.
A weakness of the book, but one I'm not sure any author could have avoided, is that the physical descriptions of Cybertron and the Transformers rarely amount to anything more than bare sketches. You might get a flash of one robot's color scheme, or a weapon they use, but unless you are already a Transformers fan you're going to have a very hard time imagining what these machines actually look like. Illustrations, even in black and white, might have been a very big help to the new Transformers reader.
Overall, if you've never been a fan of the Transformers before, this probably isn't the best place to start. At the very least, you should see the first live-action movie before you pick up the book. Transformers fans, on the other hand, will find this an interesting read. You might get angry at a few perceived violations of canon, but if you're willing to sit back and enjoy a new take on the subject, this history of the war for Cybertron is well worth reading.
Something about writing coming soon, I promise.