This novel was the basis for the television series of the same name (back on the air now), but the differences between the two are numerous. The main similarity is the machine of the novel's concept: for the same few minutes, every person on earth has a vision of the future. Both the novel and the film recount not only the result of this event (a traumatic event, as it turns out — imagine what would happen if, at a given moment, everybody on earth lost consciousness?) but also the quest to determine its cause and tease out what such an event might indicate about the nature of reality itself.
The differences between the show and the novel are great: the novel concerns a cast of scientists, not FBI agents; the vision in the novel is of a future decades from now, not a near future months from now; in the novel the event is more or less a freak accident, not seemingly orchestrated; and so on. In other words, whether you like the show or not, it's worth reading the novel.
I appreciate Sawyer for his blend of hard SF, the philosophical ramifications of science, and page-turning plots. Even without a traditional antagonist or pressing plot matters, Sawyer can build and carry suspense via philosophic or scientific speculation — no easy feat.