Each time-travel story has its own set of "rules." This one allows the time traveler to visit with his own self at another age! Yikes! And because he can go forward AND backward, he can appear to his loved ones even after the date of his death. Cool, huh?
It turns your head around a few times, but there's nothing wrong with that! It was a fun read, and it also managed to be touching and thought-provoking. I'm not sure if I want to see the movie, though. I might like to keep it in my head, just the way it is.