Really interesting sci-fi novel about the end and potentiality of humanity. The idea behind this is fascinating, and there's clearly been a lot of thought put into it - for a story of alien encounters, evolution, and the destruction of planets it's remarkably cerebral. That said, it does sag in the middle a trifle - I found the beginning third and the final quarter the most interesting, and I'm not entirely sure this story wouldn't have worked better as three separate, collected novellas/novelettes. It's close enough to being that anyway, but a more condensed, better-shaped narrative would have avoided that problem of the middle.

There's also the fact that telepathy is treated as a consistently non-scientific phenomenon. Partly this seems due to Clarke's own bias in favour of the supernatural (which he describes in retrospect in the forward, having become somewhat less credulous than he was at the time of the novel's writing), but it's a wee bit jarring for a more modern reader like myself. Science is method, after all, and there seems no reason why phenomena previously thought of as "supernatural" can't be eventually explained via rational exploration. Granted, there's the possibility that one day something may not be explained this way, but this is a tension that Clarke really doesn't explore, preferring to take the idea of the supernatural as an accepted and certain thing. This does make the story seem a wee bit dated, as do some of the racial and gender aspects, but there's an ambition to the story still that's really compelling, and the ending is amazing.