In spite of some unenthusiastic reviews, this book is brilliant. I read 100 pages the first evening, then spent all the following day glued to the story. Forget about poor characterisation or plot irrelevancies, they're not important. It's the story and action that count. The first section includes a layman's introduction to quantum physics, a subject no-one, not even physicists, understands properly. And I don't buy the theory that you can use quantum physics to travel back in time (and return again). We all know it can't be done, and never will be done.
But setting that aside, the interesting bit starts when we travel back to 14th century France, a year or so after the battle of Poitiers. Just imagine stepping out of your time machine into a world you can hardly begin to understand: the utter silence of a landscape free from the ambient noise of the 20th century, the hugeness of the trees in the primeval forest...
Then learning all the small but essentials details of medieval life and times, you get the feeling of how life really was lived, you had to be alert and strong to survive, violence and pain and sudden death are never very far away, but you can sense just through reading the text how intensely alive you would feel if you could ever go back to such a world. I think that's Mr Crichton's greatest achievement in this book. And I like reading about the reactions of people suddenly transplanted from modern times to the medieval world... it would be even better if a few medieval types could be transported in turn to the future!
I've read a few others by Crichton - Jurassic Park, the Lost World - both excellent. And try Congo - that's another masterpiece. If they ever make a film of Timeline - see it.