The middle part of a trilogy is often the hardest to write; you have the expectations and plotlines raised by the first book, while still having to set everything in place for the last act. Happily, I feel that Reynolds largely succeeded here.
In terms of timeline, Redemption Ark picks up not too long after Revelation Space finished, although straight away Reynolds throws a whole bunch of new characters at the reader. Luckily, they are all fascinating creations, from the hyper-evolved Conjoiners represented by the ruthless Skade and the repentant Clavain, to the young pilot Antoinette Bax and the brutal pig criminal Scorpio.
By the time we are actually reaquainted with the survivors from the first novel, Reynolds has embarked on several new plot strands, although all twine together into the over-arcing Inhibitors plot. For you see, the enemies of all advanced life have finally arrived, and a desperate race for the weapons capable of stopping them begins.
Reynolds maintains his knack for breaking up traditional space opera sequences with diversions into scientific theory or transhuman speculation, all without losing the tension he so masterfully builds up. If he has a flaw, it is that sometimes the human motivations, hopes and fears of his characters get somewhat lost amongst all the Big Ideas.
The novel leaves the story somewhat unresolved, in preparation for the final act of the trilogy; certainly there are more loose ends and unresolved plots than at the end of Revelation Space. Despite that, however, the journey to that point is both exciting and enjoyable, so I don't mind being herded towards the big climax. Here's hoping it maintains the high quality of the first two installments.