Read January 2012: raced through this as I found it an easy read. Liked the concept, had downloaded this after watching the first episode of the tv show, but not liking it (too much like Lost, which I found to be more annoying than entertaining, with all the new questions and few answers every episode) and it had languished in my library until I ran out of other things to read. Reminded me of many of the Michael Crichton and Robin Cook science fiction books I've read over the years - interesting premise, very readable, although clearly not high literature! The concept behind the book about whether knowing the future means that it is in unchangeable, or not, is an interesting one. I do like a good philosophically based premise.
I found the characters to be sympathetic mostly, none of them are perfect individuals, nor are they the typical Everyman character for readers to identify with, although I suppose that most people would find someone vaguely similar to identify with as there is a good range of character storylines. They are all tied up neatly at the end as well.
The only real negative was the jumping of the shark towards the end of the book - the second flash forward experienced by one of the main characters... This instantly reminded me of the ruination of the Indiana Jones movies with the aliens! Wasn't expecting that at all, and it disappointed me. If that plot line had been removed this would be a much better book.