I have a backlog of a few books that I want to write about...
After reading the first five volumes of Charlie Stross's Merchant Prince series this winter, it was hard to not get the final one, The Trade of Queens, right when it came out this spring. I don't find much that interests me in the tropes of fantasy novels, but I thought that this series was brilliant. The interweaving of plots is masterful.
The basic idea of the series is that there exist multiple parallel Earths, which are at somewhat different developmental stages because of the chaotic vagaries of history. One genetically-related group of people is able to traverse between them, an advantage they proceed to exploit for their own wealth. Miriam, a journalist born in our world, finds out she is part of this family and is thereafter a stick stirring a hornet's nest. Charlie cheerfully admits that he considers this economic and political science fiction rather than fantasy.
I saw a complaint on perhaps the Amazon page that the book suffered due to too many subplots, but I disagree completely. They are all important to the themes of the series, but also Charlie seems able to generate an endless stream of interesting, easily-differentiated characters.
It is clear that the series was planned from the beginning to build to a big finish. This is not an extended set of sequels that peter out as the writer gets bored; the Merchant Princes is more like a single novel in six volumes (don't try to start in the middle!). Charlie has written about this recently on his blog. He originally planned it as a few giant doorstops but was forced to slice it up into smaller books for marketing reasons. Other than a few pacing problems in one earlier book, he mostly pulled it off.
I don't feel that he did as much with character as he could have in acouple of thousand pages. The characters are individuals with unique personalities and attitudes, but at the deepest layer they are not developed. The quirks, the flaws, the growth, the humanity, are lacking. The main character of the series, Miriam, is last seen 30 pages from the end. This to me shows that the book is at heart not about the characters.
Charlie has described the series as "SF in fantasy drag" (excellent, long essay about writing the Merchant Prince series). It is a perfect example of the classic hard-sf formula of "Take the current world, change one feature, and describe what happens," although the changed feature is generally a new technology. Rather than musing about whether it is "really" science fiction or fantasy, my view is that it suggests a new perspective on what fiction genres mean. Stephen Jay Gould wrote about intelligence in terms of correlations. If you give a million people a test with a million questions on it, there will be correlations in their getting certain answers. The ones who are good at addition can also do subtraction. We gives names to certain clumps of correlations and define somewhat arbitrary splits between them. I suspect it is sensible to think about literary genres the same way. Certain features tend to occur together, and it is useful to give these names. It does not follow that the boundaries between them are particularly interesting or important. Merchant Princes takes features from both, but that is nothing new. China Mieville (I think) pointed out that some science fiction writers, like Alastair Reynolds, explore a mind-exploding WTF-ness that is considered more a quality of fantasy. So Al Reynolds's nanotech, genetic manipulation, lasers, spaceships, and computers are in some thematic way as much descendant from Tolkien as from Isaac Asimov. It's hardly a surprise really that excellent authors are not handicapped by narrow-minded traditions. (Although I am still not so sure about Peter Watts's vampires-in-spaceships in Blindsight.)