Blue Mars is fascinating if you're into solar system exploration, with characters visiting Mercury and the outer moons of the solar system. The passages about Mars itself tend to be extremely lengthy and, frankly, quite boring. Still, the writer creates a compelling picture about the future.
One irritating thing: the writer never addresses the fact that Mars has no magnetic field, which I understand is a key element in a planet's ability to keep its atmosphere and keep out radiation from the sun. Terraforming Mars is all good and well, but without a magnetic field it would all be pretty futile.
Also, the over-long passages about the characters' mental states and over-detailed descriptions about geography get a bit old.