This is the book that rounds things out, and gives a fuller explanation for the nature of the Hypotheticals and their long-term implications. Which in itself makes the biggest problem I had going into the book, and to an extent at the end, in that I found it difficult to be very invested in the Hypotheticals, the nature of the Spin and the wider mechanics of the universe. I thought that Spin itself was a decent exploration of those issues, and that the wider questions didn't need further answering. It's been a long time since I read Spin, and Axis didn't further whet my appetite on these matters---quite the contrary.
Yet in the end Wilson proved a lot of his mettle and made a very good book, well worth reading. Not great, though, and in the final analysis I'd say it falls significantly short of Spin and slightly short of Julian Comstock. Partly it's a problematic evoking of the big-scale issues, partly the near-future Earth sections not being as compelling. A bigger issue is that characterization doesn't seem to be as good as is usual for Wilson, partly as a consequence of the jumps around in setting and point of view I felt far less engaged by the people and their particular personality issues. It took too long for me to care about the main people for the book to really click on that level.
Still there does remain a lot of value. Wilson is great at presenting a sense of scale, creating a representation of massive spatial and chronological limits that is grander than any other fiction we're likely to see this year (Baxter is going small scale this year, Reed doesn't seem to have anything major coming out). The notion of interconnected worlds, the nature of the Hypotheticals themselves and particularly the last forty pages capture a sense of truly cosmic scale and drama.
Also great is the outgrowth of some of the blander elements from Axis, particularly the politics of Equatoria. Vox Core is a great construction, and quite complex--on the one hand more genuinely democratic and egalitarian than current societies, but also far from a one-note utopia--they have a single linked conscience that makes it easy to tolerate the slaughter of rivals, and they are in basis a descendant of a fanatic faction that finds it easy to reinforce their own rather biased assumptions. The dynamic of how this plays out, from the slaughter of the Farmers to their own destruction through misplaced veneration of the Hypotheticals, is very strong material, and has a lot of value to say on religious both explicitly and symbolically.
In the end I still can't say that Spin sequels were really needed, but there's a lot of pleasure and interest to see this series finish out. I'm quite interested to see where Wilson goes after this.
Similar to and better than: City at the End of Time by Greg Bear
Similar to and worse than: Spin by Robert Charles Wilson