I can't believe I haven't reviewed this on here yet! Slant is one of my top-five favorites. I read it while I was camping in rainy Door County, and I averaged a hundred pages a day (it usually takes a week to do that much). It was totally engrossing. Sure, the plot wasn't overloaded with suspense or action or anything like that (until the climax, when things speed up a little), but the density of the near-future world that Bear creates is incredible. The words he invents, the language he uses to describe things, all the references to other books and people such as "Alive Contains a Lie" by Kiss of X (a book that one of Slant's character's is reading), and the realistic, every-day characters made me feel like this novel was actually taking place in the future.
The plot deals with a group of rich snobs using nanotechnology to reverse medical and psychological therapy and create chaos in America; the policewoman, a self-aware AI, and a psychiatrist who become involved; a team of saboteurs seeking to infiltrate and destroy Omphalos, the group's giant headquarters; a middle-class family, and a prostitute, who are also entangled. The book moves at a steady, reasonable pace which adds to the realism. There are no action heroes (or even regular heroes) - everyone is a normal person who becomes imbroiled in strange events. The science, while complex, is written clearly and concisely, and never gets in the way of characters or story. Bear's five or six plots only come together loosely towards the end of the book, but are strongly tied together thematically.
As for the ending, which other reviewers have complained about, it didn't bother me. I guess I don't care much for endings anyway -my own fiction supports that. Some of the plots are left to come to their own conclusions, or for the reader to decide. This is another part of the realism I experienced - in real life there is no explosive climax to every "episode" of our lives, everything just keeps on moving.
This is a fascinating book, and I will gladly read it a third time as soon as I have the opportunity.