This is the weakest of the Revelation Space novels, which is a shame, because it is the last and it ends more with a whimper than a bang. There are two main flaws; one is that it doesn't really end the story of humanity's encounter with the Inhibitors at all and that feels unsatisfactory. There is a clear need for a fourth book to wrap things up properly, but we aren't going to get it.

The other, possibly greater, flaw is hardly unique to this book, or this writer, and has to do with a common narrative technique in the contemporary novel; multiple, apparently unrelated story threads and perspectives that eventually weave together. The risk is that the reader will relate better to one of these perspectives or find one story-line more interesting and therefore grow somewhat bored when away from it. This is only a risk - it doesn't always work out that way. The first book I remember having this trouble with was Gibson's Mona Lisa Overdrive, which had three threads. The preceding volume, Count Zero, had two and was fine. In Philip Reeves' Bartimaeus trilogy, the first book has only two threads. In either the second or third (can't remember which) a third is introduced and it dilutes things too much. In Suzette Hill's Bones books, the Rector is much less fun than his cat and dog. In Hamilton's Night's dawn trilogy there are so many threads it's difficult even to count them...Back in Reynolds' saga, events near and on Hela are dull compared to those on or near Ararat, which makes 600+p feel longer than it did in any of the prior volumes. That said, this is not a bad book, just not outstanding.

Looking at the whole series, humanity faces a series of threats: The Melding Plague, the Inhibitors and at the very end the species meets greenfly. Each of these is a more profound problem than the previous one. It reminds me of the following sequence: Acid Rain, Ozone depletion, climate change. Each of these is also an escalation of the threat and each requires greater global co-operation to get a successful solution. Honestly, I don't think we are doing as well at that now as the various human factions in Reynolds' 2600s-2700s future - and they could have done a lot better. There is a profound difference between the two sets of problems (more significant than that of scale, since both threaten the whole species) - Reynolds presents a set of ultimately alien generated threats; back down on Earth, right now, we face the consequences of our own choices.