No spoilers here, but the plot itself is excellent, and has Hamilton's trademark 'big finish' - I've actually read this trilogy (Nights Dawn, of which this is the first book) a couple of times with a few years gap between and I still find it a great read.
This was actually my first Hamilton book (I've since read almost everything he's written). As other reviewers have said, I almost gave up at the start, the first few pages are a space battle and in my opinion (as someone who reds a LOT of sci-fi)it's very hard to read. BUT STICK WITH IT! The story that unfolds puts those first few pages into context and really every chapter kicks the plot up a notch.
There's some great concepts at play here, Hamilton explores two divergent attitudes of human development and portrays them both believably. He builds a good solid reality for his characters to exist in, and after that difficult first few pages I found it easy to get lost in the story (always the sign of a good book for me). There are some excellent characters, though overall I think his later novels (Pandora's Star/Judas Unchained/Void Trilogy) represent the best character work Hamilton has done, these characters are no less engaging for being a tiny bit less developed. I still think the Nights Dawn trilogy has some of his best Villains (and semi-villains) Hamilton has ever written, and that's where this novel really shines in my opinion, his construction of believable 'bad guys', that aren't just evil for no reason or sadistic for no reason, they all have motivation and purpose and personalities. The overall plot encompasses elements of faith, spirituality, science, religion, belief, technology and of course Hamilton's (seemingly) favourite topic of politics. It's also got really interesting "What If?" qualities that go a bit beyond any single sci-fi story I've otherwise encountered, which those who know the story will understand, but I don't want to go into without spoiling it for others.
There are actually a few plotlines going on here, which is why that first space battle is so difficult, it's actually the very, very, end of a plotline that's only ever vaguely mentioned in the rest of the book, but in Hamilton's way it gets folded back into the main plot at various points in quite a 'butterfly effect'. In strict terms it has nothing to do with the main plot at all, neither does most of the first half of the book, except that it all does and it all weaves back into everything else later on - Have Faith!
If you have read any Hamilton before, you will love this book. If you've not, then think of it like Baxter (but less bleak) mixed with Clarke, (but with better characters) and Niven, (for the scope of ideas and 'human' characters), and Banks (for his scope of political/human social structures and development). I have to say of all the authors I've read over the years, Hamilton is one of the very few that I would unquestioningly buy anything else he publishes, and that was largely built on the strength of this, the first of his books I read.