I'm in two minds about this book. For thoughtfulness and originality it probably deserves four stars. For enjoyable readability it's more like two. I've compromised on three, but really it's two and a half, rounding up.

The ideas here are interesting. The sheer scale of the story, the way it's put together as a mix of report and diary and explanation, over multiple species and multiple planets and in both life and afterlife... this is something to really challenge the reader, and I tend to appreciate books that do that. But it's just so fucking turgid. The pacing is dire (especially in the first half), and the characters are admirable but largely unattractive. George, for example, is supposed to be some paragon that everyone can't help but follow, but mostly he seems to me smugly tiresome and in need of a good slap. His sister Rachel, far more flawed, is also far more interesting and the only character I actually gave a damn about - the substantial portion of the book that is her diary is the most enjoyable part of it, and I genuinely did enjoy her sections.

Lessing has written other books that I've liked far more. This is the most ambitious of the lot, and it's not I think nearly as successful as the rest I've read. I can't help but wonder what would change if she wrote it today... how much refinement and clarity could be put into it. (It's in dire need of both.) Even so, there are still flashes of the extraordinary here... worth reading, perhaps, but once is enough.