The movie is a formally disciplined piece of work, a triumph of movie syntax, made with a sense of rhythm and pace, and Gyllenhaal, who is always good at conveying anxiety, gives Stevens's desperation a comic edge.
This time, Jones has more money and greater studio expectations behind him, so what begins as another existential head trip that puts ideas before spectacle eventually morphs into something trite and compromised -- hard sci-fi gone soft.
"Source Code" is perfectly enjoyable as a swiftly moving thriller, and Gyllenhaal is effective as a mystified fellow who eventually engages himself - and us - in putting the pieces of the puzzle together.
With a twisty, mind-bending plot that frequently changes direction and occasionally overreaches, "Source Code" wouldn't work at all without a cast with the determination and ability to really sell its story.
The script by Ben Ripley doesn't come up with enough obstacles to throw in the hero's path, and his budding romance with the doomed Christina feels more like a studio mandate than an organic development.
Ripley's intricate script and Jones's brisk direction invite us to climb aboard and enjoy the ride. But if you want to dig deeper, there is some serious stuff about a guy lost in fragments of time, groping towards a sense of his own identity.
Solid execution and some provocative ideas can't save Source Code from a fatal hubris, as it thinks itself far more clever than it actually is and assumes it's earned emotions at which it's only hinted.