The movie starts very slowly. There's hardly anything interesting in the first hour. During that time, I almost fell asleep in the theatre. Despite the commendable efforts to make it comply with the predictions of modern physics like time dilation, twin paradox, etc. the plot is still full of gaps and utterly nonsensical actions which defy your logic. The "scientific" references to quantum mechanics, general relativity and string theory (this one is rather implicit...) in the dialogues are very pretentious and most of the time plain silly. The only parts of the movie that would evoke interest and probably keep you awake are as usual about human drama, power struggle and emotional encounters. In this regard, all the efforts to make it compatible with the laws of modern physics become useless and a waste of time. Indeed, I have yet to see any movie that can pull it off since "Contact." In this regard, I'd rather see "dumb" sci-fi movies which concentrate on drama like the first and 2nd gen Star-Trek than this sort of half-ass physics-wanna-be stuff which fail to address your imagination.

On the positive side the plot is clear, unobstructed and easily understandable despite the references to theoretical physics. Compared to sheer crap like "Cloud Atlas" that certainly deserves a praise hence my three stars for the rating.