Yes it does - in a way! After reading quite a few Stephen Kings years ago, I got a bit fed up with the whole horror/fantasy thing and haven't been there for a long while. I heard mention of this book and thought I'd give it a try. It is not like his previous works and while it is fantasy in the sense that it deals with time travel it is also - in an odd way - credible. Makes you wonder "what if ..."
Quizzy - I understand your problem! Heavy books, especially when you are reading in bed, are a nuisance. My advice - get a Kindle then they all weigh the same! Happy reading, folks, hope you all get some good books for Christmas.
I was a bit disappointed. In the end he changed nothing, it would have been more interesting if he saved Kennedy, and came back to a much better future. Also as someone who reads a lot of SF, the SF elements seemed almost tagged on with no real exploration of the mechanics of the time travel.