This is one of those movies...
...that starts out really good and ends up pretty bad. Some others I can think of: Final Destination and Hollowman. They all have good concepts and the first 30 minutes have me hooked, then they lose focus and get kind of ridiculous. I thought the beginning of this movie was sooo creepy, I was sure I'd love the whole thing, but I was disappointed.
Tomorrow's just your future yesterday!