The acting of both Gyllenhall and Monoghan is spot-on, bringing emotion and depth to a movie that could have been too stiff and scientific due to the out-there technology and concept. The emotion they bring echoes one of the most important questions of the movie: If you knew you only had eight minutes to live, what would you do with that time? While this kind of thinking could run you ragged, it does encourage the concept of living in the moment, going for what you want, and not letting life or opportunities pass you by.
The subtle changes that Ripley writes for each of the travels back in time that Gyllenhall's character experiences are also a study in human behavior. Our little communication quirks, our laziness, and how we tend to disengage and float through life. This movie shakes the characters awake and gives them a second chance.
A clever plot combined with crazy-smart technology and solid acting equals a movie worth watching.