Doomsday Book

An awful book. The entire story was filled with problems all the characters were unable to fix. In fact, only the ending accomplished anything. Physiological problems are simply not reasonable conflicts in any storytelling medium.
Time travel in general is boring science fiction. However, this book did introduce some important time travel innovations. It does not save the book, but it is worth mentioning. (Thankfully, I have only read one other time travel book REPLAY, which was significantly better).