A Nebula winner, and one of a handful of hard SF books considered a classic. I'll admit that hard SF doesn't gel well with my personal reading tastes with its emphasis on scientific explanation and frequently stock characters; however, I have enjoyed some immensely, such as _The Forge of God_, and this novel only proves that Hard SF CAN be both technically fascinating and be superby piece of literature and characterization as well.
Initially, Timescape caught my attention with its central premise of a dying future (well, 1998, the future when the book was written) finding a way through tachyon messages of contacting the past (1962). But the book does tend to tread water for a long time, and some of the character conflicts get a bit tiresome. But in the finale, which contains a stunning surprise, the strange science at last coalesces into a emotionally stirring vision of time as a landscape. It was at this moment that I saw the book itself become a whole-and an admirable whole. As the thoughtful afterward points out, the book tackles many different types of stories, not all of which will appeal to every reader. Give it shot, even if Hard SF insn't your thing.