Titan (John Varley) ** readable if prepared to skim
The plot was seriously porn-esque. Sex figured largely in "Press Enter" and "The Persistence of Vision," but it contributed to the characters and themes. Here, sex just shows up randomly with porn-bop beats.
The setting read like a description of an engineering diagram, as in "twelve cables twenty kilometers in diameter rose from the ground at approximately forty-degree angles." I don't pretend to be anything other than the village idiot of spatial logic, but I think even normal people would object to this nonsense. Plus everything is so damn big that my head translates every measurement into "damn big in diameter for a hell of a distance."
The sentient life-forms and languages and stuff were pretty cool, though. That's what kept me going. I would never have concocted sentient blimps on my own (with eyes! and live animals that digest food for it! and sentient animals that hitch rides and "pay" their way by moving the food from stomach to stomach). Or centaurs with a singing language, or murderous solitary emaciated angels. Of course, I wouldn't have equipped the centaurs with three sexual organs each. I mean, it's just hard to keep a straight face.
In conclusion, this book should have been pitched as a movie. The world should look pretty fantastic onscreen (I'm imagining Sky Captain and the World of Tomorrow), and then it could be the most expensive porn ever.