Commonwealth saga.
But yeah. It's a failing of Hamilton, where he has amazing ideas but just can't write a satisfactory end to the story.
It was in that Commonwealth saga, with Pandora's Star and Judas Unchained, but equally in the Night's Dawn Trilogy (Reality Dysfunction, Neutronium Alchemist and the Naked God).
I haven't read any of his other books, set in that universe, so maybe these are better?
Which is a shame.
Hamilton really can write and have believable, truly alien aliens, but he also has a knack of thinking about what some different sorts of technology would mean to a human culture.
Only those endings.
Oh well. It's the journey, not the destination, that counts.