I've finally finished the Mars trilogy. I'll admit that I'm a slow reader, but this was a long journey even for me. Blue Mars is not an easy read, and a bit more difficult to complete than the first two books of the trilogy. There was a sense of urgency in those, where the human presence on Mars felt tenuous and subject to radical, even epochal change in minute intervals of time. In Blue Mars, human civilization has more or less succeeded on Mars and the questions turn more toward the nature of Martian civilization than what it must do to survive (Red Mars) or thrive (Green Mars). So, it's a slower read.
That's not to say that it's a slog. Robinson has a gift for beautiful prose that can captivate the attentive reader even at its densest. Not every passage is equally brilliant, of course, but there are moments of stunning brilliance. The first that comes to mind graces about a dozen pages in the latter third of the novel, where a theory of history is laid out by one of the viewpoint characters (Zo, a daughter of the cynical magnate Jackie Boone) -- a remarkable synthesis of current historiographical theories, with a healthy dose of scientifictional speculation, charting human progress from feudalism to capitalism to socialism and beyond, with all kinds of mixtures, disruptions, and simultaneities in between. Another moving set of passages, this time over a hundred pages, comes when Sax Russell becomes motivated and eventually succeeds in countering the effects of advanced senescence by biological means. In the meantime, he and his great nemesis, Ann Clayborne, come to terms. This sequence is a magnificent conclusion to the trilogy, bringing the focus back to the First Hundred (or what's left of them) and resolving the great conflict between the forces of cultural advancement (represented by Sax Russell) and the love of the unspoiled (represented by Ann Clayborne). The curiosity and love of the universe that the two share ultimately brings them together without forcing them to agree in the end -- indeed, this kind of unity is a microcosm of the success of Martian civilization (and the expanded human civilization across the solar system) as a whole -- holding itself together (with varying degrees of tenuousness) while taking pains to avoid homogeneity.
So, ultimately, Blue Mars answers the promises of Red Mars and Green Mars -- the fate of humanity on that sister world reaches a satisfying climax while the eternal drive toward improvement pushes humanity to (the potential of) even greater heights. There are some side plots that one is impatient to bypass (speaking for myself, at least), and the epilogue is a bit of a let-down. But in the end, I think the whole trilogy is worth reading, not as a gateway to the simple pleasures of keeping tabs on favorite characters' lives (which the majority of fiction seems to aim at) but as a way of engaging with an entirely plausible vision of the forces that drive humanity to do what it does.
As the Arthur C. Clarke blurb on the cover of Red Mars promises, this really should be essential reading for would-be settlers of Mars. Why? Because Mars is our chance to get it right this time. The protagonists of the trilogy don't get it right all the time, but they do better than their forebears. They're also a model for the new colony ships setting out to do even better in nearby star systems.