One of the best things science fiction can offer is a fresh analysis of what it means to be human. This books delivers on that analysis -- in spades. Ordinarily, a review shouldn't provide a synopsis, but since one is not provided by Amazon.com, I'll provide a brief one.
The setting is Earth, one thousand years in the future. The world is populated by humans ("premen"), genetically perfected humans ("trumen"), genetically modified soldiers ("mumen") and gods, who are part human, part celestial matter. Many centuries prior, premen had created these other beings, who have now nearly displaced the premen. By order of Earth's god, they are to be relocated to a distant and inhospitable world. Two premen children, a boy and a girl, struggle against their deportation and discover that they may have the key to fighting against the gods, if only they have enough time.
This book is more than just action and kaleidoscopic settings. It's about what it means to be human, what rewards and suffering struggle brings, and about friendship, loyalty and hope. Think of it as s.f.'s equivalent to "The Shawshank Redemption."
2008 CAVEAT TO MY 2000 REVIEW. Over the years as I've reflected on this book I've come to realize its moral failure, which is a big one. SPOILER ALERT. The evil gods are overcome at the end by the Ultiman, the ultimate man, a God-like figure that supposedly combines the best of humanity with God-like powers. However, the Ultiman was created by flawed humans, the same people who created the evil gods in the first place. How long before the Ultiman stops defending humanity and begins to tyrannize the multiverse, just like his predecessor gods? (Varley's "Titan" series brings this problem out in bold relief.) We've heard of the banality of evil, but it seems there's a corollary of the banality of evil of absolute power.