I have found that when I finish a really long, good book and start a second one, I suffer from 'book fatigue' and it takes me longer to get into and appreciate the following book. Having finished Memories of Ice by Steven Erikson, I felt that this would happen, but fortunately it did not. Either I paced myself with that book (not deliberately- it was good, but I couldn't read as much given my busy schedule) or Crystal Rain succeeds at capturing the reader quickly and effectively. Let's be optimistic and say that Buckell has done his job well.
A cool thing I found was the description of the airship flights. I always imagined them to be nice and smooth like most airplane flights nowadays, but I realize that this is a bogus expectation. Airships must be extremely light and thus any gust of wind will cause them to shake about. Additionally, if you go very high up, you will have trouble breathing as the main 'cabin' is not pressurized. In hindsight, all this makes sense and are just part of the difficulties of high-altitude, open-air airship travel, but it's something I had not thought about that Buckell pointed out.
The plot is very straightforward, which is actually kind of disappointing after reading a massive, twisted, epic fantasy novel. It does move along at a nice pace and you can pick it up very quickly. The simplicity of the plot is refreshing, but only up to a point. Once you finish it, you think to yourself: oh, that's it?
The details are always a mystery of course. For example, you don't know how the Nanagadans are going to repel the Aztecan invasion, until they do, but you do know that the main plot device, the Ma Wi Jung, will save the day. The only potentially interesting plot twist or development is Oaxyctl's last moments, but even those aren't that impressive.
The characters could have been a bit better fleshed out, in my opinion. The story focuses heavily on John deBrun and Oaxyctl, but there are other viewpoint characters as well. John has amnesia and is trying to recover his memories, but it doesn't really feel like he is trying hard. It doesn't seem like a driver for his persona. Instead he focuses on his family, but even then he is able to let go rather quickly. At the end of the book, you have a better idea of his motivations, but even then it feels like something is missing.
Oaxyctl, on the other hand, is a much better developed character. He is Azteca (see Setting), but has crossed over the mountains to join the mongoose-men in fighting the Azteca. However, as is is made very clearly early on, he is actually a spy and he intends to capture/torture/etc John in particular. Circumstances bring them together and they begin to learn from each other. It seems to me that Oaxyctl gets the better deal as he slowly opens up and talks about his wife, his home across the mountains, and his gods. By the end of the story he is conflict: does he follow his god, whom he now knows is false, or does he turn and follow his new friend? Redemption stories like that are immensely interesting when done properly, regardless of whether the 'bad' guys redeem themselves or fail to do so. Oaxyctl's growth through the story is probably the best part of the book. My only regret is that the final execution could have been a little better, more emotional, perhaps.
The rest of the characters are, unfortunately, pretty flat and unchanging. I didn't care about the Prime Minister or the military commander and even John's son, Jerome, is difficult to connect to. Jerome begins to grow when he's in Frenchitown, but he's quickly stunted.
Another minor qualm I had was that there is a strong dialect among nearly all of the people in the story. Word choice and dialect can be used very effectively to set apart a person or group of people, and I like how it was pulled off in The Wheel of Time. Unfortunately, for this book it looks like everyone has the same dialect so you can't use it to distinguish people (with the rare exception like John) and it's fairly heavy. I would have preferred a lighter dialect that is used only sparingly to highlight maybe one or two characters. I suppose that as it is, it doesn't detract from the story, but it does require a little extra effort to parse what people are saying.
Setting / World Building
I find it difficult to think of it as a science fiction story given the very little science we see until the very end. It's like being in the Dream of Peter F. Hamilton's The Dreaming Void. This is sci-fi, though: there are spaceships (and airships), guns, physical enhancements, wormholes, and alien species. But the society there has lived for hundreds of years and (most of) the original people who remember are now dead. Hence, what you have is a population that has grown up and thinks the aliens are gods and the world gets a more magical or fantastical feel. I described it on Goodreads as 'old' sci-fi technology amidst a colonial-type Caribbean world where gods/aliens and religion/technology blend together. It's a very interesting combination and I would have liked to see a bit more of the world (and more airships!).
The setting of this story is probably the best aspect of it. Not only is there plenty of sci-fi talk (there's a whole backstory that is alluded to and I don't mention here), but it's also set in a nice tropical climate, like good ol' Puerto Rico. I don't see settings like those often in speculative fiction so that was pretty neat.
The book has some flaws in weak characters and generic plot line, but other than that it's a pretty decent book with very good pacing. Considering that this is a debut novel from 2006 and he has continued writing, Buckell can only have improved.
Perhaps this wasn't the best book to pick in order to get a feel for his style? I have mixed feelings about whether or not to recommend this book. However, Buckell actually provides the entire first third of the book as a free preview. So perhaps your best bet is to check that out and make your own decision from there.