Backtracking a bit, Book One was character inception and plot layer. The book was full of plot history and character development. The sheer richness of the beginning of the series was gorgeous. It seemed like it had unlimited possibilities. Then came Book Two. Here, the cast was still growing and the plot was still thickening... the stage was being set!
Now you come to Book Three... the curtain rises... and the stage explodes with everything thus far set-up. Idle idiosyncrasies and personal histories shape the plot is ways I never would have thought. The inter-personal relationships become more involved, also thus shaping the plot. Alternate-human cultures are explored is beautiful detail, as are the world in which the future humans live. Clever are the crew when confronted with difficulties on the ship, on the planet or between each other. Some lingering questions are answered about the rings mysteries.
Book Three is a definite confirmation that the Rings of the Master series is character driven. Book Three sets the bar QUITE high for Book Four.